Axial length measurement monitor

ABSTRACT

An OCT axial length measurement device is configured to measure an area of the retina within a range from about 0.05 mm to about 2.0 mm. The area can be measured with a scanned measurement beam or plurality of substantially fixed measurement beams. The OCT measurement device may comprise a plurality of reference optical path lengths, in which a first optical path length corresponds to a first position of a cornea, and a second optical path length corresponds to a second position of the retina, in which the axial length is determined based on a difference between the first position and the second position. An axial length map can be generated to determine alignment of the eye with the measurement device and improve accuracy and repeatability of the measurements. In some embodiments, the OCT measurement device comprises a swept source vertical cavity surface emitting laser (“VCSEL”).

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 63/200,718, filed Mar. 24, 2021, entitled “AXIAL LENGTH MEASUREMENTMONITOR”, the entire disclosure of which is incorporated herein byreference.

The subject matter of the present application is related toPCT/US2019/038270, filed on Jun. 20, 2019, entitled “MINIATURIZEDMOBILE, LOW COST OPTICAL COHERENCE TOMOGRAPHY SYSTEM FOR HOME BASEDOPHTHALMIC APPLICATIONS”, published as WO/2019/246412 on Dec. 26, 2019,the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Recently developed light therapies have been proposed for decreasing andpossibly reversing increases in axial length of the eye. It would behelpful to have improved methods and apparatus to measuring refractiveerror in order to determine appropriate therapies to treat theprogression of refractive error such as myopia.

The prior approaches to measuring refractive error can be less thanideal. Although cycloplegia can be used to freeze the accommodativeresponse in an effort to provide a more reliable measure of refractiveerror, many patients do not like to be dilated which can make dailymeasurements with cycloplegic an unrealistic goal. Also, subjectiverefraction is based on visual acuity can be less than ideal because thelens of the eye can accommodate which decreases the accuracy andrepeatability of manifest refractions. While objective refractionmeasurements from devices such as autorefractors can automatically findthe hyperfocal correction, midway between the plus and minus sides ofthe depth of field, these devices are susceptible to patientaccommodation and can provide less than ideal results.

Although it has been proposed to measure changes in axial length todetermine changes to the refractive error of the eye, the priorapproaches to measuring axial length can be less than ideal in at leastsome respects. Some prior approaches to measuring axial length can relyon optical coherence tomography systems that are more complex than wouldbe ideal. Also, at least some of the prior approaches to measuring axiallength can rely on a difference in distance between the cornea and asingle point on the retina. Work in relation to the present disclosuresuggests that the retina can be less smooth than would be ideal, whichcan result in less than ideal results. At least some prior studies haveshown that the correlation between changes in axial length andrefractive error is only reasonably good when a large population ofsubjects (e.g. 50 to 100 subjects) are tested regularly over a period of6 to 12 months. Consequently, changes in axial length of a particularchild with a prior axial length monitor may less than ideally correlatewith myopia progression, and may not be well suited for monitoringmyopia progression and adjusting treatment.

Work in relation to the present disclosure suggest that prior approachesto measuring axial length may measure an approximately 50 micron zone atthe fovea, and that retinal thickness can vary substantially (e.g. byapproximately 50 microns or more) when measured over such a small zone,both on the same subject, and also on a population of subjects withsimilar ocular biometry.

In light of the above, improved methods and apparatus are needed todetermine changes in refractive error and axial length of the eye.

SUMMARY

The presently disclosed methods and systems provide improvedmeasurements of the axial length of the eye. In some embodiments, anarea of the retina is measured to provide a more accurate axial lengthmeasurement. The area of the retina may comprise a maximum dimensionacross, e.g. a diameter, within a range from about 0.05 mm to about 2.0mm. The area can be measured with a scanned measurement beam orplurality of substantially fixed measurement beams. In some embodiments,an OCT measurement device comprises a plurality of reference opticalpath lengths, in which a first optical path length corresponds to afirst position of a cornea, and a second optical path length correspondsto a second position of the retina, in which the axial length isdetermined based on a difference between the first position and thesecond position. In some embodiments, an axial length map is generated,which can be used to determine alignment of the eye with the measurementdevice and can improve accuracy and repeatability of the measurements.In some embodiments, the OCT measurement device comprises a swept sourcevertical cavity surface emitting laser (“VCSEL”).

INCORPORATION BY REFERENCE

All patents, applications, and publications referred to and identifiedherein are hereby incorporated by reference in their entirety and shallbe considered fully incorporated by reference even though referred toelsewhere in the application.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the features, advantages and principles of thepresent disclosure will be obtained by reference to the followingdetailed description that sets forth illustrative embodiments, and theaccompanying drawings of which:

FIG. 1A shows a simplified diagram of the human eye;

FIG. 1B shows a perspective view of a monocular optical coherencetomography (OCT) device for measuring eyes of a user, in accordance withsome embodiments;

FIG. 2 shows a schematic of a system allowing a patient to measure axiallength at multiple time points and to communicate the results, inaccordance with some embodiments;

FIG. 3A shows a handheld optical coherence tomography device utilizingBluetooth communication, in accordance with some embodiments;

FIG. 3B shows a handheld OCT device utilizing the Global System forMobile Communications (GSM), in accordance with some embodiments;

FIG. 4 shows a perspective view of a binocular OCT device for measuringeyes of a user, in accordance with some embodiments;

FIG. 5 shows a block diagram of the binocular OCT device illustratingvarious components within the handheld unit body, in accordance withsome embodiments;

FIG. 6 shows a schematic of an optical configuration that may beimplemented with the OCT binocular, in accordance with some embodiments;

FIG. 7 shows a block diagram of the optical configuration configured onan optical layout board, in accordance with some embodiments;

FIG. 8 shows a perspective view of a modular binocular OCT device, inaccordance with some embodiments;

FIG. 9 shows a perspective/cut-away view of the binocular OCT device, inaccordance with some embodiments;

FIG. 10 shows another perspective/cut-away view of the binocular OCTdevice, in accordance with some embodiments;

FIG. 11 shows an overhead/cut-away view of the binocular OCT devicecomprising an eye position sensor, in accordance with some embodiments;

FIG. 12 shows an OCT device with two reference arms, in accordance withsome embodiments;

FIG. 13A shows signal intensity and frequency for an OCT device with twosignals simultaneously received with one or more detectors, e.g. abalanced pair, in accordance with some embodiments;

FIG. 13B shows signal frequency broadening due to chirp of the sweptsource;

FIG. 14 shows measurement depth of an axial length monitor, inaccordance with some embodiments;

FIG. 15 shows a fixation target configured to change color in responseto user alignment, in accordance with some embodiments;

FIG. 16 shows an array of VCSELs coupled to a plurality of opticalfibers, in accordance with some embodiments; and

FIG. 17 shows a VCSEL array imaged into the eye, in accordance with someembodiments.

DETAILED DESCRIPTION

The following detailed description and provides a better understandingof the features and advantages of the inventions described in thepresent disclosure in accordance with the embodiments disclosed herein.Although the detailed description includes many specific embodiments,these are provided by way of example only and should not be construed aslimiting the scope of the inventions disclosed herein. For example,although reference is made to measuring an axial length of an eye, themethods and apparatus disclosed herein can be used to measure many typesof samples, such as other tissues of the body and non-tissue material.While reference is made to generating maps of axial length, the methodsand apparatus disclosed herein can be used to generate images of oculartissue, such as cross sectional or tomographic images of an eye, such asimages of one or more of the retina, the cornea, or the lens.

In some embodiments, the term axial length refers to the distancebetween the corneal apex to the retinal pigment epithelium (RPE) of theeye. Measurement of axial length along the optical axis of the eye canbe used in order to determine paraxial focal length and optical power ofrefractive devices that may be provided to bring the eye to emmetropia,that is move the best focused image to the surface of the retinalpigment epithelium. Axial length can also be measured along any othersuitable direction, and may be expressed as a mean value that is anaverage of measurements of axial length along a plurality of directionsfrom the RPE to the corneal apex comprising the foveola, the fovea oreven the entire macula. Also, in some embodiments, the axial length canbe determined at least in part based on curvature of the cornea, forexample where a plurality of axial lengths is determined along anannular region of the cornea and a corresponding annular region of themacula

The presently disclosed methods, systems and devices are well suited formeasuring an axial length of the eye. Work in relation to the presentdisclosure suggests that axial length can be used for measuring changesin eye length caused by scleral remodeling, and eye models have beendeveloped to convert axial length into refractive error. In someembodiments, the eye models are configured to include the anterior andposterior curvatures of the cornea, the corresponding cornea thickness,as well as the location and power of the crystalline lens of the eye. Insome embodiments, the power of the crystalline lens is substantiallyconstant, and variations of anterior chamber depth can be assumed basedon the eye model or measured directly. The eye model can be convertedinto a regression curve and included as an algorithm in an application.

The presently disclosed methods, systems and devices are well suited forcombination with PCT/US2019/038270, filed on Jun. 20, 2019, entitled“MINIATURIZED MOBILE, LOW COST OPTICAL COHERENCE TOMOGRAPHY SYSTEM FORHOME BASED OPHTHALMIC APPLICATIONS”, published as WO/2019/246412, theentire disclosure of which has been incorporated by reference, and whichis well suited for modification in accordance with the presentdisclosure. Such a system can be modified in accordance to measure axiallength by modifying the ray path to measure changes in OPD of up to +/−3mm (e.g., 21+/−3 mm).

Measurement of axial length may be carried out over a zone on theretinal surface that may have a diameter of 0.05 to 2.0 mm, preferably0.10 to 1.5 mm. In some optical designs, a scanning system utilizing forexample a movable mirror may be deployed, performing a plurality of Ascans. A mean axial length may be computed from these individualmeasurements. Alternatively or in combination, a plurality ofsubstantially fixed beams can be used to measure the axial length.

In some embodiments, the axial length measurement device is configuredfor monitoring myopia progression. Work in relation to the presentdisclosure suggests that myopia progression takes place substantially bydeepening the vitreous compartment, although sometimes changes incorneal curvatures may also make a moderate contribution. Work inrelation to the present disclosure also suggests that axial lengthcorrelates strongly with myopia progression in children, and thepresently disclosed methods and apparatus are well suited for monitoringmyopia progression in children.

In some embodiments, the OCT device comprises an axial length monitorwith an accuracy of +/−25 microns, a resolution of 10 microns and arepeatability of +/−15 microns.

In some embodiments, the OCT device is configured to measure a change inspherocylindrical equivalent of +/−0.07 D and detect a change of 0.03 D,based on relationships between axial length and refraction as describedherein. In some embodiments, this performance enables the device tomonitor changes in refraction on a monthly basis in children, such asAsian children, whose myopia progression rate can be about 0.9 D/year,on average.

In some embodiments, the OCT axial length measurement device is able todetect efficacy of myopia inhibition therapies rapidly, so that a changein therapy can be made before myopia in the patient approaches the levelof high myopia (>−5 D), and in many embodiments, much lower levels ofmyopia, such as not more than 1.0 D of myopia, e.g. a refraction of −1.0D.

In some embodiments, the OCT AL measurement device comprises one or moreof the following features as shown in Table 1.

TABLE 1 Features of OCT AL measurement device. Durable, compact size 7.5cm diameter × 25 cm length Weight < 750 g Passes all safety, shippingand durability testing required by EU Accuracy of +/− 25 microns, aresolution of 10 microns and a repeatability of +/− 15 microns Rechargedfrom a laptop or charger Data downloaded to smart device with user Appthrough API Data can then be uploaded into a cloud-based database Lowcost enables broad distribution, increasing accessibility Portable andeasy for children to handle and use Ensures reliable, actionableinformation Data accessible 24/7 from anywhere and can be integratedwith other databases AI-enhanced data mining and analytics

In some embodiments, the OCT AL measurement device comprises a monocularconfiguration, in which axial length is measured from corneal apex tothe retinal pigment epithelial (RPE) layer, the patient is capable offixating, and auto alignment or self-alignment based on visual cues.

The presently disclosed systems, devices and methods are well suited forincorporation with prior OCT approaches. The OCT interferometer maycomprise one or more of a time domain OCT interferometer, a swept sourceOCT interferometer, spectral domain OCT interferometer or a multiplereflectance OCT interferometer. Although reference is made to a sweptsource VCSEL with a limited range of sweeping and the use of a pluralityof VCSELs, the light source may comprise any suitable light source suchas a MEMS tunable VCSEL capable of sweeping over a range of wavelengthsfrom about 20 nm to about 100 nm or more. Although reference is made toaxial length maps, in some embodiments, the OCT measurement systems andapparatus are configured to generate 3D tomographic images of the corneaand retina. In some embodiments, the 3D tomographic images of the retinacomprise high resolution image of the retina, with a spatial resolutionalong the OCT measurement beam within a range from 4 to 25 microns, forexample with resolution within a range from 2 to 10 microns.

The presently disclosed systems and methods can be configured in manyways. In some embodiments, the OCT system comprises a binocular device,in which one eye is measured and the other eye is presented with astimulus such as a fixation stimulus. Alternatively, the OCT system maycomprise a monocular device, in which one eye is measured at a time andonly the measured eye is presented with a fixation stimulus, althoughthe fellow eye may be covered with an occluder, for example.

The compact OCT system disclosed herein is well-suited for use with manyprior clinical tests, such as axial length measurements. In some cases,the OCT system is used by the patient, or by a health care provider. Inmany instances the patient can align himself with the system, althoughanother user can align the patient with the system and take themeasurement. In some embodiments, the OCT system is integrated withprior software and systems to provide additional information tohealthcare providers and can provide alerts in response to changes inaxial length. The alerts are optionally sent to the patient, caregiver,and health care providers when corrective action should be taken such asa change in ocular therapy, vision stimulation therapy, medication,dosage, or a reminder to take medication.

As used herein, the “term axial length” (“AL”), refers to an axialdistance of the eye from the cornea of the eye to the retina of the eye.In some embodiments, the AL is measured as a distance from the anteriorsurface of the cornea to the retinal pigment epithelium (“RPE”).

As used herein, the term “corneal thickness” (“CT”) refers to athickness of the cornea between an anterior most corneal layer, e.g. thetear film, and a posterior most layer, e.g. the corneal endothelium.

As used herein, the term “retinal thickness” (“RT”) refers to athickness of the retina between layers used to evaluate the thickness ofa retina of a patient. The RT may correspond to a thickness of theretina between an anterior surface of the retina and external limitingmembrane, for example.

As used herein, the term “retinal layer thickness” (“RLT”) refers to thethickness of one or more optically detectable layers of the retina. Theoptically detectable layers of the retina may comprise a thickness ofthe retina extending between the external limiting membrane and theretinal pigment epithelium, for example.

FIG. 1A shows a simplified diagram of the human eye. Light enters theeye through the cornea 10. The iris 20 controls the amount of lightallowed to pass by varying the size of the pupil 25 that allows light toproceed to the lens 30. The anterior chamber 40 contains aqueous humor45 which determines the intraocular pressure (IOP). The lens 30 focuseslight for imaging. The focal properties of the lens are controlled bymuscles which reshape the lens. Focused light passes through thevitreous chamber, which is filled with vitreous humor 55. The vitreoushumor maintains the overall shape and structure of the eye. Light thenfalls upon the retina 60, which has photosensitive regions. Inparticular, the macula 65 is the area of the retina responsible forreceiving light in the center of the visual plane. Within the macula,the fovea 70 is the area of the retina most sensitive to light. Lightfalling on the retina generates electrical signals which are passed tothe optic nerve 80 and then to the brain for processing.

Several disorders give rise to reduced optical performance of the eye.In some cases, the axial length of the eye is undesirably long, which isrelated to myopia of the patient. In some cases, the intraocularpressure (TOP) is either too high or too low. This is caused, forinstance, by too high or too low of a production rate of aqueous humorin the anterior chamber or drainage of aqueous humor from the anteriorchamber, for example. In other cases, the retina is too thin or toothick. This arises, for instance, due to the buildup of fluid in theretina. Diseases related to an abnormal retinal thickness (RT) includeglaucoma, macular degeneration, diabetic retinopathy, macular edema anddiabetic macular edema, for example. In some cases, a healthy range ofRT is from 175 thick to 225 μm thick. In general, abnormalities ineither the TOP or the RT or both are indicative of the possible presenceof one of several ophthalmological diseases. Additionally, the TOP orthe RT vary in response to ophthalmological treatments or otherprocedures. Therefore, it is desirable to have a means to measure theTOP and/or RT for diagnosis of ophthalmological diseases and to assessthe effectiveness of treatments for a given patient. In some cases, itis desirable to measure the thickness of one or more retinal layers, forexample the thickness of a plurality of layers. In addition, it isdesirable to process data obtained from an OCT system to assist inidentifying fluid pockets or regions in the eye, as these may indicate achange in eye health.

The systems and methods disclosed herein relate to the use of opticalcoherence tomography (OCT) to measure the AL at multiple points in time.For instance, a patient measures their AL at multiple time points totrack the progression of an ophthalmological disease such as myopia overtime. As another example, a patient measures their AL at multiple timepoints to track their response to a photo-stimulation therapy or othertreatment. In some cases, the system produces an alert when one or morerecent measurements of the AL deviate significantly from previousmeasurements. In some cases, the system alerts the patient or thepatient's physician of the change. In some instances, this informationis be used to schedule a follow-up appointment between the patient andphysician to, for instance, attempt a treatment of an ophthalmologicalcondition, discontinue a prescribed treatment, or conduct additionaltesting.

FIG. 1B shows a perspective view of a monocular optical coherencetomography (OCT) device 100 for measuring eyes of a user, in accordancewith some embodiments. The OCT device 100 includes a head 202, a base204, and a neck 206 therebetween. The head 202 is connected to the neck206 by a coupling 208 that allows articulation of the head 202 in someembodiments. The head may be covered with a housing that enclosesoptical modules, scanning modules, and other related circuitry andmodules to allow the OCT device 100 to measure eyes of a user, one eyeat a time.

In some embodiments, the head 202 further includes a lens 210, andeyecup 212, and one or more LED lights 214. The lens 210 may beconfigured to direct one or more light sources from within the head 202to focus on the retina of an eye. The eyecup 212 may be configured tolocate the head of a patient, and thereby locate an eye of a patient forscanning and testing. The eyecup 212 may be rotatable, so that aprotruding portion 216 may be located adjacent to an eye of a patientand extend along the side of the head (e.g., adjacent the patient'stemple) when the patient's head is properly oriented to the OCT device100. The eyecup 212 may be coupled to a sensor configured to detect therotational orientation of the eyecup 212. In some embodiments, the OCTdevice 100 is configured to detect the rotational orientation of theeyecup 212 and thereby determine whether the patient has presented herright eye or left eye for scanning and measuring. More particularly, insome embodiments, the protruding portion 216 of the eyecup 212 mayextend to be adjacent to either the right temple or the left temple of apatient, and thereby determine which eye of the patient is beingmeasured. In some embodiments, eyecup 212 comprises a patient support.The patient support may comprise a headrest or a chinrest, eitheralternatively or in combination with the eyecup 212.

In some embodiments, a coupling 208 connects the head 202 to the neck206 and allows a pivotal movement about the coupling. The coupling 208may be any suitable coupling, which may be rigid, articulating,rotational, or pivotal according to embodiments. In some instances, thecoupling includes a threaded fastener and a threaded nut to tighten thehead against the neck in a desired orientation. The threaded nut may beoperable by hand, and may comprise a knurled knob, a wing nut, a starnut, or some other type of manually operated tightening mechanism. Thecoupling may alternatively or additionally comprise any suitable memberthat allows adjustment of the angle of the head relative to the neck,and may include a cam, a lever, a detent, and may alternatively oradditionally include friction increasing structures, such as roughenedsurfaces, peaks and valleys, surface textures, and the like.

FIG. 2 shows a schematic of a system allowing a patient to measure theAL at multiple time points and to communicate the results, in accordancewith some embodiments. The patient looks into a handheld OCT device 100to obtain a measurement of the AL. In some embodiments, the handheld OCTdevice comprises optics 102, electronics 104 to control and communicatewith the optics, a battery 106, and a transmitter 108. In someinstances, the transmitter is a wired transmitter. In some cases, thetransmitter is a wireless transmitter. In some cases, the handheld OCTdevice 100 communicates the results via a wireless communication channel110 to a mobile patient device 120 such as the patient's smartphone orother portable electronic device. In some cases, the wirelesscommunication is via Bluetooth communication. In some embodiments, thewireless communication is via Wi-Fi communication. In other embodiments,the wireless communication is via any other wireless communication knownto one having skill in the art. Although reference is made to wirelesscommunication, in some embodiments the OCT device connects by wiredcommunication to the patient mobile device and the patient mobile deviceconnects wirelessly to a remote server such as a cloud based server.

In some cases, the results are fully processed measurements of the AL.In some cases, all processing of the OCT data is performed on thehandheld OCT device. For instance, in some embodiments, the handheld OCTdevice includes hardware or software elements that allow the OCT opticalwaveforms to be converted into electronic representations. In somecases, the handheld OCT device further includes hardware or softwareelements that allow processing of the electronic representations toextract, for instance, a measurement of the AL.

In some cases, the results are electronic representations of the rawoptical waveforms obtained from the OCT measurement. For instance, insome embodiments, the handheld OCT device includes hardware or softwareelements that allow the OCT optical waveforms to be converted intoelectronic representations. In some cases, these electronicrepresentations are then passed to the mobile patient device for furtherprocessing to extract, for instance, a measurement of the RT.

In some cases, the patient receives results and analysis of the ALmeasurement on the patient mobile app. In some embodiments, the resultsinclude an alert 122 alerting the patient that the results of themeasurement fall outside of a normal or healthy range. In some cases,the results also include a display of the measured value 124. Forinstance, in some cases a measurement of the AL produces a result with aspecific value in millimeters (“mm”), e.g. 23.6 mm. In some instances,this result corresponds to a change in axial length outside a desiredrange. This causes the system to produce an alert and to display themeasured value on the patient mobile app. In some embodiments, the alertis transmitted to a healthcare provider, such as a treating physician.In some embodiments, the results also include a chart 126 showing ahistory of the patient's AL over multiple points in time.

In some instances, the patient mobile device communicates the results ofthe measurement via a communication means 130 to a cloud-based or othernetwork-based storage and communications system 140. In someembodiments, the communication means is a wired communication means. Insome embodiments, the communication means is a wireless communicationmeans. In some cases, the wireless communication is via Wi-Ficommunication. In other cases, the wireless communication is via acellular network. In still other cases, the wireless communication isvia any other wireless communication known to one having skill in theart. In specific embodiments, the wireless communication means isconfigured to allow transmission to or reception from the cloud-based orother network-based storage and communications system.

Once stored in the cloud, the results are then transmitted to otherdevices, in specific embodiments. In some cases, the results aretransmitted via a first communication channel 132 to a patient device150 on the patient's computer, tablet, or other electronic device. Insome embodiments, the results are transmitted via a second communicationchannel 134 to a physician device 160 on the patient's physician'scomputer, tablet, or other electronic device. In some instances, theresults are transmitted via a third communication channel 136 to ananalytics device 170 on another user's computer, tablet, or otherelectronic device. In some embodiments, the results are transmitted viaa fourth communication channel 138 to a patient administration system orhospital administration system 180. In some cases, each of the deviceshas appropriate software instructions to perform the associatedfunction(s) as described herein.

In specific embodiments, the first communication channel is a wiredcommunication channel or a wireless communication channel. In somecases, the communication is via Ethernet. In other cases, thecommunication is via a local area network (LAN) or wide area network(WAN). In still other cases, the communication is via Wi-Fi. In yetother cases, the communication is via any other wired or wirelesscommunication channel or method known to one having skill in the art. Insome embodiments, the first communication channel is configured to allowtransmission to or reception from the cloud-based or other network-basedstorage and communications system. In some cases, the firstcommunication channel is configured to only allow reception from thecloud-based or other network-based storage and communications system.

In some cases, the second communication channel is a wired communicationchannel or a wireless communication channel. In some instances, thecommunication is via Ethernet. In specific embodiments, thecommunication is via a local area network (LAN) or wide area network(WAN). In other embodiments, the communication is via Wi-Fi. In stillother embodiments, the communication is via any other wired or wirelesscommunication channel or method known to one having skill in the art. Insome cases, the second communication channel is configured to allowtransmission to or reception from the cloud-based or other network-basedstorage and communications system. In some embodiments, the secondcommunication channel is configured to only allow reception from thecloud-based or other network-based storage and communications system.

In specific cases, the third communication channel is a wiredcommunication channel or a wireless communication channel. In someinstances, the communication is via Ethernet. In other instances, thecommunication is via a local area network (LAN) or wide area network(WAN). In still other instances, the communication is via Wi-Fi. In yetother instances, the communication is via any other wired or wirelesscommunication channel or method known to one having skill in the art. Insome embodiments, the third communication channel is configured to allowtransmission to or reception from the cloud-based or other network-basedstorage and communications system. In some cases, the thirdcommunication channel is configured to only allow reception from thecloud-based or other network-based storage and communications system.

In some embodiments, the fourth communication channel is a wiredcommunication channel or a wireless communication channel. In somecases, the communication is via Ethernet. In other cases, thecommunication is via a local area network (LAN) or wide area network(WAN). In still other cases, the communication is via Wi-Fi. In yetother cases, the communication is any other wired or wirelesscommunication channel or method known to one having skill in the art. Insome instances, the fourth communication channel is configured to allowtransmission to or reception from the cloud-based or other network-basedstorage and communications system. In other cases, the fourthcommunication channel is configured to only allow reception from thecloud-based or other network-based storage and communications system.

A determination of the AL can be performed at many locations. Forinstance, a determination of the AL may be performed on the handheld OCTdevice. In some cases, a determination of the AL is performed at alocation near to the handheld OCT device, such as by a smartphone orother portable electronic device. In some embodiments, a determinationof the AL is performed on the cloud-based storage and communicationssystem. In some instances, the handheld OCT device is configured tocompress measurement data and transmit the compressed measurement datato the cloud-based storage and communications system. Alternatively orin combination, other components of the OCT system, such as a mobiledevice operatively coupled to the OCT device, can be configured tocompress the measurement data and transmit the compressed measurementdata to the cloud-based storage and communication system, for example.

In some embodiments, the patient receives results and analysis of the ALmeasurement on the patient device 150. In some instances, the resultsinclude an alert 152 alerting the patient that the results of themeasurement fall outside of a normal or healthy range. In some cases,the results also include a display of the measured value 154. Forinstance, in some cases, a measurement of the AL produces a result of23.6 mm. This result may correspond to an increase in axial lengthindicating an increase in myopia. In some cases, this causes the systemto produce an alert and to display the measured value of 23.6 mm on thepatient device. In specific cases, the results also include a chart 156showing a history of the patient's AL over multiple points in time. Insome cases, the patient device also displays instructions 158 for thepatient to follow. In some instances, the instructions instruct thepatient to visit their physician. In some embodiments, the instructionsinclude the patient's name, date of most recent AL measurement, and nextscheduled visit to their physician, for example.

In some embodiments, the patient's physician receives the results andanalysis of the AL measurement on the physician device 160. In someinstances, the results include an alert 162 alerting the physician thatthe results of the measurement correspond to a potentially significantchange from baseline. In some cases, the results also include an alert164 informing the physician of the patient's measurement. In someembodiments, the alert includes a suggestion that the physician call thepatient to schedule an appointment or to provide medical assistance. Insome embodiments, the results also include a display 166 showing themost recent measurements and historical measurements for each of thephysician's patients. For instance, in some instances, a measurement ofthe AL produces a result of 23.6 μm. This result corresponds to a changefrom a baseline value indicating a possible progression of myopia. Insome cases, this causes the system to produce an alert and to displaythe measured value of 23.6 mm on the physician app, or an amount ofincrease in axial length from a prior measurement. In specific cases,the physician device also displays contact and historical information168 for each of the physician's patients.

In some embodiments, the other user receives results and analysis of theAL measurement on the analytics device 170. In some instances, the otheruser is a researcher investigating the efficacy of a new form oftreatment. In other cases, the other user is an auditor monitoring theoutcomes of a particular physician or care facility. To protect thepatient's privacy, in some cases the analytics device is restricted toreceive only a subset of a given patient's information. For instance,the subset is restricted so as not to include any personally identifyinginformation about a given patient. In some cases, the results include analert 172 alerting or indicating that a large number of abnormal orundesirable measurements have been obtained in a specific period oftime. In some cases, the results include one or more graphicalrepresentations 174 of the measurements across a population of patients.

In some cases, the results and analysis on the analytics device comprisedisease information such as a physician-confirmed diagnosis. In somecases, the results and analysis comprise anonymized patient data such asage, gender, genetic information, information about the patient'senvironment, smoking history, other diseases suffered by the patient,etc. In some cases, the results and analysis comprise anonymizedtreatment plans for the patient, such as a list of light therapies,prescribed medications, treatment history, etc. In some cases, theresults and analysis comprise measurement results, such as the resultsof an AL measurement, patient refraction (eyeglass prescription), avisual function test, or the patient's compliance with a course oftreatment. In some cases, the results and analysis comprise data from anelectronic medical record. In some cases, the results and analysiscomprise diagnostic information from visits to a patient's medicalprovider, such as the results of an axial length OCT scan acquired bythe patient's medical provider.

In some embodiments, the patient's clinical, hospital, or other healthprovider receives results and analysis of the AL measurement on thepatient administration system or hospital administration system 180. Insome cases, this system contains the patient's electronic medicalrecord. In some cases, the results and analysis provide the patient'shealth provider with data allowing the provider to update the treatmentplan for the patient. In some instances, the results and analysis allowthe provider to decide to call the patient in for an early office visit.In some instances, the results and analysis allow the provider to decideto postpone an office visit.

In some embodiments, one or more of the patient device, physiciandevice, and analytics device includes a software application comprisinginstructions to perform the functions of the patient device, physiciandevice, or analytics device, respectively, as described herein.

FIG. 3A shows a handheld OCT device utilizing short-range wirelesscommunication, in accordance with some embodiments. In some embodiments,the handheld OCT device 100 comprises optics 102, electronics to controland communicate with the optics 104, a battery 106, and a wirelesstransmitter 108. In some cases, the wireless transmitter is a Bluetoothtransmitter. In some instances, the results from one or more ALmeasurements are stored on the handheld OCT device until an authorizeduser, such as the patient or another person designated by the patient,opens the patient mobile device on a smartphone or other portableelectronic device. Once opened, the patient mobile device applicationestablishes wireless communication with the handheld OCT device. In somecases, the communication is via a Bluetooth wireless communicationchannel 110. In some instances, the handheld OCT device communicates theresults via the Bluetooth channel to a mobile patient device 120 on thepatient's smartphone or other portable electronic device.

In some instances, the results include an alert 122 alerting the patientthat the results of the measurement fall outside of a desired range. Inspecific embodiments, the results also include a display of the measuredvalue 124. For instance, a measurement of the AL produces a result of23.6 in some cases. This result may fall outside of a desired range. Insome cases, this causes the system to produce an alert and to displaythe measured value of 23.6 mm on the patient mobile app. In specificembodiments, the results also include a chart 126 showing a history ofthe patient's AL over multiple points in time.

In some cases, the patient mobile device application communicates theresults of the measurement via a wireless communication means 130 to acloud-based or other network-based storage and communications system140. In some instances, the wireless communication is via Wi-Ficommunication. In other cases, the Wi-Fi communication is via a secureWi-Fi channel. In still other cases, the wireless communication is via acellular network. In specific embodiments, the cellular network is asecure cellular network. In other embodiments, the transmittedinformation is encrypted. In some cases, the communication channel isconfigured to allow transmission to or reception from the cloud-based orother network-based storage and communications system. In some cases,data is stored on the smartphone or other portable electronic deviceuntil the smartphone or other portable electronic device connects to aWi-Fi or cellular network.

In some cases, the patient mobile device application has a feature whichnotifies the patient, or another person designated by the patient, whentoo much time has elapsed since the patient mobile device applicationwas last opened. For instance, in some cases this notification occursbecause the patient has not acquired measurements of the AL as recentlyas required by a measuring schedule set by their physician or otherhealthcare provider. In other cases, the notification occurs because thehandheld OCT device has been storing the results of too manymeasurements and needs to transmit the data to the patient's smartphone.In specific embodiments, the patient mobile device applicationcommunicates with the cloud-based or other network-based storage andcommunications system to display a complete set of patient data.

FIG. 3B shows a handheld OCT device capable of communicating directlywith a cloud-based storage and communication system without reliance ona user device such as a smartphone, in accordance with some embodiments.In some embodiments, the handheld OCT device 100 comprises optics 102,electronics to control and communicate with the optics 104, a battery106, and a wireless transmitter 108. In some cases, the wirelesstransmitter is a GSM transmitter. In some instances, the results fromone or more AL measurements are stored on the handheld OCT device. Insome cases, the GSM transmitter establishes wireless communication witha cloud-based or other network-based storage and communications system140 via a wireless communication channel 114. In specific cases, thewireless communication is via a GSM wireless communication channel. Inother embodiments, the system utilizes third generation (3G) or fourthgeneration (4G) mobile communications standards. In such cases, thewireless communication is via a 3G or 4G communication channel.

In specific embodiments, the patient mobile device 120 receives theresults of the measurement via a wireless communication means 130 fromthe cloud-based or other network-based storage and communications system140. In some cases, the wireless communication is via Wi-Ficommunication. In some cases, the Wi-Fi communication is via a secureWi-Fi channel. In other cases, the wireless communication is via acellular network. In some cases, the cellular network is a securecellular network. In specific instances, the transmitted information isencrypted. In some embodiments, the communication channel is configuredto allow transmission to or reception from the cloud-based or othernetwork-based storage and communications system.

Once obtained from the cloud-based or other network-based storage andcommunications system, the results of the AL measurement are viewed inthe patient mobile application, in some instances. In some cases, theresults include an alert 122 alerting the patient that the results ofthe measurement fall outside of a normal or healthy range. In someinstances, the results also include a display of the measured value 124.For instance, in some cases a measurement of the AL produces a result of23.6 mm. This result may fall outside of a desired range as describedherein. In specific embodiments, this causes the system to produce analert and to display the measured value of 23.6 mm on the patient mobileapplication. In some embodiments, the results also include a chart 126showing a history of the patient's AL over multiple points in time.

In some cases, the patient mobile device application has a feature whichnotifies the patient, or another person designated by the patient, whentoo much time has elapsed since the patient mobile device applicationwas last opened. For instance, in some cases this notification occursbecause the patient has not acquired measurements of the AL as recentlyas required by measuring schedule set by their physician or otherhealthcare provider. In other cases, the notification occurs because thehandheld OCT device has been storing the results of too manymeasurements and needs to transmit the data to the patient's smartphone.In specific embodiments, the patient mobile device communicates with thecloud-based or other network-based storage and communications system todisplay a complete set of patient data.

In some cases, the handheld OCT device comprises both a short-rangetransmitter and a GSM, 3G, or 4G transmitter. In some instances, theshort-range transmitter is a Bluetooth transmitter. In some cases, thehandheld OCT device communicates directly with the patient mobile deviceapplication on a smartphone or other portable electronic device throughthe Bluetooth wireless communication channel. In some embodiments, thehandheld OCT also communicates with the cloud-based or othernetwork-based storage and communications system through the GSM, 3G, or4G wireless communication channel. In specific cases, the cloud-basedsystem then communicates with the patient mobile device applicationthrough a Wi-Fi, cellular, or other wireless communication channel.Alternatively, the Bluetooth transmitter is built into a dockingstation. In some instances, this allows for the use of older devices forpatients who lack a smartphone. In some cases, the docking station alsoincludes a means for charging the battery of the handheld OCT device.

In some cases, the handheld OCT device of FIGS. 3A and 3B is configuredto be held in close proximity to the eye. For instance, in specificembodiments, the device is configured to be held in front of the eyewith the detector at a distance of no more than 200 mm from the eye. Inother embodiments, the devices are configured to be held in front of theeye with the detector at a distance of no more than 150 mm, no more than100 mm, or no more than 50 mm from the eye. In specific instances, thehandheld OCT devices further comprise housing to support the lightsource, optical elements, detector, and circuitry. In some cases, thehousing is configured to be held in a hand of a user. In some cases, theuser holds the devices in front of the eye to direct the light beam intothe eye. In some instances, the devices include a sensor to measurewhich eye is being measured. For instance, in specific embodiments, thedevices include an accelerometer or gyroscope to determine which eye ismeasured in response to an orientation of the housing. The devicesoptionally include an occlusion structure coupled to the housing and thesensor that determines which eye is measured. The occlusion structureoccludes one eye while the other eye is measured. In some cases, thedevices include a viewing target to align the light beams with a portionof the retina. For instance, in specific embodiments, the devicesinclude a viewing target to align the light beams with a fovea of theeye. In some cases, the viewing target is a light beam. In some cases,the viewing target is a light emitting diode. In other cases, theviewing target is a vertical cavity surface emitting laser (VCSEL). Instill further cases, the viewing target is any suitable viewing targetas will be known to one having ordinary skill in the art.

The optical components described herein are capable of beingminiaturized so as to provide the handheld OCT device with a reducedphysical size and mass, as described herein, as will be appreciated byone of ordinary skill in the art.

In some embodiments, the handheld OCT devices of FIGS. 3A and 3B aresmall enough and light enough to be easily manipulated with one hand bya user. For instance, in some embodiments, the device has a mass withina range from about 100 grams to about 500 grams, although the device maybe heavier and may comprise a mass within a range from about 500 gramsto about 1000 grams, for example. In some embodiments, the device has amass within a range from about 200 grams to about 400 grams. In someembodiments, the device has a mass within a range from about 250 gramsto about 350 grams. In specific embodiments, the device has a maximumdistance across within a range from about 80 mm to about 160 mm. Inspecific embodiments, the device has a maximum distance across within arange from about 100 mm to about 140 mm. In specific embodiments, thedevice has a width within a range from about 110 mm to about 130 mm. Insome embodiments, the maximum distance across comprises a length. Insome embodiments, the device has a width less than its length. Inspecific embodiments, the device has a width within a range from about40 mm to about 80 mm. In specific embodiments, the device has a widthwithin a range from about 50 mm to about 70 mm. In specific embodiments,the device has a width within a range from about 55 mm to about 65 mm.

FIG. 4 shows a perspective view of a binocular OCT device 4900 formeasuring eyes of a user, in accordance with some embodiments. Thebinocular OCT device 4900 comprises a first adjustable lens 4916-1 thatis optically coupled to an OCT measurement system and a first fixationtarget configured within a handheld unit body 4903 (e.g., a housing),both of which are hidden from view in this figure. Similarly, a secondadjustable lens 4916-2 may be optically coupled to the OCT measurementsystem and a second fixation target (hidden). The first adjustable lens4916-1 may be part of a first free space optics that is configured toprovide a fixation target and measure an axial length of the user's eye,whereas the second adjustable lens 4916-2 may be part of a second freespace optics that is configured to only provide a fixation target so asto reduce a number of components in the binoculars OCT device 4900. Forinstance, while both free space optics provide the user with a fixationtarget, only one of the free space optics is used to measure the axiallength as the binocular OCT device 4900 may be turned upside down, i.e.inverted, after the user measures a first eye such that the user maymeasure the other eye.

The binocular OCT device 4900, in this embodiment, comprises aninterpupillary distance (IPD) adjustment mechanism 4905 that isaccessible on the exterior of the handheld unit body 4903. In thisembodiment, the IPD adjustment mechanism 4905 comprises two components,a first component 4905-1 that adjusts the distance between the lenses4916-1 and 4916-2 to match the IPD of a user's pupils when the userplaces the binocular OCT device 4900 front of the user's eyes when theeye cups 4901-1 and 4901-2 rest on the user's face.

This IPD can be set by a healthcare professional and locked intoposition for the user to measure one or more of the AL, cornealthickness, or retinal thickness at home. Alternatively, the IPD can beuser adjustable. A switch 4904 may be used to adjust the lenses 4916-1and 4916-2 to match a user's refraction, i.e. eyeglass prescription.Alternatively, a mobile device, such as a tablet can be used program therefraction of each eye of the patient. For example, the user may fixateon the first fixation target with one eye and a second fixation targetwith another eye, and the movable lenses adjusted to the user'srefraction. The switch 4904 may selectively adjust the assemblies of thelenses 4916-1 and 4916-2 within the handheld unit body 4903 to changethe positioning of the lenses 4916-1 and 4916-2. These positions can beinput into the device by a health care professional and stored in aprocessor along with an orientation from an orientation sensor asdescribed herein. The device can be inverted, and the process repeated.Alternatively, or additionally, the prescription for each eye can bestored in the processor and the lenses adjusted to the appropriaterefraction for each eye in response to the orientation of theorientation sensor.

Both of the components 4905-1 and 4905-5 may be implemented as one ormore wheels that the health care professional manually rotates.Alternatively, the IPD adjustment mechanism 4905 may be motorized. Inthis regard, the components 4905-1 and 4905-5 may be configured asdirectional switches that actuate motors within the handheld unit body4903 to rotate gears within the handheld unit body 4903 based on thedirection in which the user directs the switch.

The switch 4904 can be used to adjust the focusing of the binocular OCTdevice 4900. For example, because the focal change effected byadjustment of the lenses 4916-1 and 4916-2 can be measured in acustomary unit of refractive power (e.g., the Diopter) by adjustment ofthe lenses 4916-1 and 4916-2. The Diopter switch 4906 may also comprisea directional switch that actuates a motor within the handheld unit body4903 to rotate gears within the handheld unit body 4903 based on thedirection in which the healthcare professional directs the switch toadjust the refractive power of the binocular OCT device 4900. As thebinocular OCT device 4900 may comprise an electronic device, thebinocular OCT device 4900 may comprise a power switch 4906 to controlpowering of the binocular OCT device 4900.

Each of the eyecups 4901-1 and 4901-2 can be threadedly mounted andcoupled to the housing to allow adjustment of the position of the eyeduring measurements. Work in relation to the present disclosure suggeststhat the eyecups can be adjusted by a healthcare professional and lockedin place to allow sufficiently reproducible positioning of the eye forAL measurements as described herein. Alternatively, or in combination,an eye position sensor, such as a Purkinje image sensor can be used todetermine a distance from the eye to the OCT measurement system.

The binocular OCT device 4900 may comprise appropriate dimensions andweight for in home measurements and for the user to take the binocularOCT system on trips. For example, the binocular OCT system may comprisea suitable length, a suitable width and a suitable height. The lengthcan extend along an axis corresponding to the users viewing direction.The length can be within a range from about 90 mm to about 150 mm, forexample about 130 mm. The width can extend laterally to the length andcan be within a range from about 90 mm to about 150 mm for example about130 mm. The height can be within a range from about 20 mm to about 50mm, for example. In some embodiments, the length is within a range fromabout 110 mm to 210 mm, the width within a range from about 100 mm to200 mm and a height within a range from about 50 mm to about 110 mm. Insome embodiments, a maximum distance across the device is within a rangefrom about 200 mm to about 350 mm, for example approximately 300 mm.

The weight of the binocular OCT system can be within a range from about1 pound to two pounds, e.g. 0.5 kg to about 1 kg.

The binocular OCT device 4900 can be configured to be dropped and stillfunction properly. For example, the binocular OCT device can beconfigured to be dropped from a height of about 30 cm and still functionso as to perform AL measurements accurately, e.g. with a change inmeasured AL of no more than the repeatability of the measurements. Thebinocular OCT system can be configured to be dropped from a height ofabout 1 meter without presenting a safety hazard, for example from glassbreaking.

FIG. 5 shows a block diagram of the binocular OCT device 4900illustrating various components within the handheld unit body 4903, inaccordance with some embodiments. For instance, the binocular OCT device4900 comprises free space optics 4910-1 and 4910-2. Each of the freespace optics 4910-1 and 4910-2 comprises a fixation target 4912 for itsrespective eye that allows the user to fixate/gaze on the target whilethe user's AL is being measured, and to allow fixation with the othereye, so as to provide binocular fixation. The fixation target maycomprise an aperture back illuminated with a light source such as anLED, (e.g., a circular aperture to form a disc shaped illuminationtarget, although a cross or other suitable fixation stimulus may beused. The free space optics 4910-1 and 4910-2 may also compriserefractive error (RE) correction modules 4911-1 and 4911-2,respectively, that comprises the lenses 4916-1 and 4916-2, respectively.These lenses can be moved to preprogrammed positions corresponding tothe refractive error of the appropriate eye. A peripheral board 4915-1and 4915-2 in the free space optics modules 4910-1 and 4910-2 provideselectronic control over a motorized stage 4914-1 and 4914-2,respectively to correct for the refractive error of the respective eyeviewing the fixation target of the binocular OCT device 4900.

As discussed herein, the binocular OCT device 4900 may comprise eye cups4901-1 and 4901-2 that may be used to comfortably rest the binocular OCTdevice 4900 on the user's face. They may also be configured to block outexternal light as the user gazes into the binocular OCT device 4900. Theeye cups 4901 may also comprise eye cup adjustment mechanisms 4980-1 and4980-2 that allow the health care professional and optionally the userto move the eye cups 4901-1 and 4901-2 back and forth with respect tothe handheld unit body 4903 to comfortably position the eye cups on theuser's face and appropriately position each eye for measurement.

In some embodiments, the binocular OCT device 4900 comprises a fiberedinterferometer module 4950 that comprises a single VCSEL or a pluralityof VCSELs 4952. The one or more VCSELs 4952 are optically coupled to afiber distribution module 4953, which is optically coupled to fiberMach-Zender interferometer 4951. With embodiments comprising a pluralityof VCSELs 4952, the VCSELS may each comprise a range of wavelengthsdifferent from other VCSEL 4952 in the plurality in order to extend aspectral range of light. For example, each VCSEL 4952 may pulse laserlight that is swept over a range of wavelengths for some duration oftime as described herein. The swept range of each VCSEL 4952 maypartially overlap an adjacent swept range of another VCSEL 4952 in theplurality as described herein. Thus, the overall swept range ofwavelengths of the plurality of VCSELs 4952 may be extended to a largerwavelength sweep range. Additionally, the firing of the laser light fromthe plurality of VCSELs 4952 may be sequential. For example, a firstVCSEL of the plurality of VCSELs 4952 may sweep a laser pulse over afirst wavelength for some duration. Then, a second VCSEL of theplurality of VCSELs 4952 may sweep a laser pulse over a secondwavelength for some similar duration, then a third, and so on.

The laser light from the one or more VCSELs 4952 is opticallytransferred to the fiber distribution module 4953, where a portion ofthe laser light is optically transferred to a fiber connector 4960 foranalysis in a main electronic board 4970. The fiber connector 4960 mayconnect a plurality of optical fibers from the fiber distribution module4953 to the fiber connector module 4960. Another portion of the laserlight is optically transferred to an optical path distance correction(OPD) module 4940 and ultimately to the free space optics 4910-1 fordelivery to a user's eye and measurement of the user's eye with aportion of the measurement arm of the Mach-Zender interferometer. Forexample, the OPD correction module 4940 may comprise a peripheral board4943 that is controlled by the main electronic board 4970 to actuate amotorized stage 4942 to change the optical path distance between theuser's eye, a coupler of the Mach-Zender interferometer and the one ormore VCSELs 4952. The OPD correction module 4940 may also comprise afiber collimator 4941 that collimates the laser light from the VCSELs4952 before delivery to the user's eye, and the fiber collimator can betranslated with the OPD correction module 4940.

A controller interface 4930 may be used to receive user inputs tocontrol the binocular OCT measurement system. The controller interfacemay comprise a first controller interface 4930-1 and a second controllerinterface 4930-2. The controller interface 4930 may comprise a triggerbutton mechanism that allows a user to initiate a sequence of steps toalign the eye and measure the retina as described herein. Alternativelyor in combination, the device may be configured with an auto-capturefunction, such that the data is automatically acquired when the deviceis aligned to the eye within appropriate tolerances.

In some embodiments, the binocular OCT device 4900 comprises a scannermodule 4990 that scans the laser light from the one or more VCSELs 4952in a pattern (e.g., a stop and go scan pattern, a star scan pattern, acontinuous scan pattern, a Lissajous scan pattern, or a flower scanpattern (rose curve)). For example, a peripheral board 4991 of thescanner module 4990 may be communicatively coupled to the mainelectronic board 4970 to receive control signals that direct the scannermodule 4992 to scan the pulsed laser light from the VCSELs 4952 in apattern to perform an optical coherence tomography (OCT) measurement onthe user's eye. The scanning module 4990 may comprise a sealing window4992 that receives the laser light from the fiber collimator 4941 andoptically transfers the laser light to a free space two-dimensionalscanner 4993, which provides the scan pattern of the laser light. Thetwo-dimensional scanner may comprise a scanner as described herein, suchas a two-axis galvanometer, or a two axis electro-static scanner, forexample. When present, the sealing window 4992 may be used to keep theinternal components of the binocular OCT device 4900 free of dirt and/ormoisture. The laser light is then optically transferred to relay optics4994 such that the scanned laser light can be input to the user's eyevia the free space RT optics 4910-1. In this regard, the scanned laserlight may be transferred to a hot mirror 4913 such that infrared lightmay be reflected back towards the hot mirror, the scanning mirror andfocused into an optical fiber tip coupled to the collimation lens. Thehot mirror 4913 generally transmits visible light and reflects infraredlight, and may comprise a dichroic short pass mirror, for example.

The scanner and associated optics can be configured to scan any suitablysized regions of the retina, such as regions comprising the fovea. Insome embodiments and scanner and associated optics are configured toscan the cornea while the retina is scanned. In some embodiments, thescanner is configured to scan the retina with a scanning pattern, suchas a predetermined scanning pattern in response to instructions storedon a processor such as the controller. For example, the scanner can beconfigured to scan the retina over an area comprising a maximum distanceacross within a range from about 0.05 to 2.0 mm, for example. Themaximum distance across may comprise a diameter, and can be within arange from about 0.1 mm to about 1.5 mm. The dimensions of cornealscanning can be similar. The scanning region of the retina may comprisean area larger than maps of AL in order to account for slight errors inalignment, e.g. up to 0.5 mm in the lateral positioning of the eye inrelation to the OCT system, for example in order to compensate foralignment errors, e.g. by aligning the map based on the measuredposition of the eye. The size of the OCT measurement beam on the retinacan be within a range from about 25 microns to about 75 microns. In someembodiments, the mirror is moved with a continuous trajectorycorresponding to a scan rate on the retina within a range from about 10mm per second to about 200 mm per second, and the scan rate can bewithin a range from about 50 mm per second to about 200 mm per second.The displacement of the beam during an A-scan can be within a range fromabout 2 to 10 microns, for example. The beams for each of a plurality ofA-scans can overlap. In some embodiments, the mirror moves continuouslywith one or more rotations corresponding to the trajectory of the scanpattern and the swept source VCSEL turns on and off with a suitablefrequency in relation to the size of the beam and the velocity of thebeam on the retina. In some embodiments each of the plurality of A-scansoverlaps on the retina during at least a portion of the scan pattern.

In embodiments where the one or more VCSELs comprises a plurality ofVCSELs, the plurality of VCSELs can be sequentially scanned for eachA-scan, such that the measurement beams from each of the plurality ofVCSELs overlaps on the retina with a prior scan, and the cornea may bescanned similarly. For example, each of the sequentially generated beamsfrom each of the plurality of VCSELs from a first A-scan can overlapwith each of the sequentially generated beams from each of the pluralityof VCSELs from a second A-scan along the trajectory.

As described herein, the binocular OCT device 4900 may comprise an IPDadjustment via the components 4905-1 and/or 4905-2. These components maybe communicatively coupled to a manual translation stage IP adjustmentmodule 4982 that perform the actuation of the free space optics modules4910-1 and 4910-2, so as to change a separation distance between thefree space optics modules and adjust the IPD.

The main electronic board 4970 may comprise a variety of components. Forexample, a photodetector 4972 may be used to receive laser lightdirected from the VCSELs 4952 through the fiber connector 4960 as wellinterfering light reflected from the user's eye. The fiber connector4960 may comprise a module 4961 that couples a plurality of opticalfibers, for example four optical fibers, to a plurality of detectors,for example five detectors. The fiber connector 4960 may also comprisean interferometer clock box 4962 (e.g. an etalon) that may be used inphase wrapping light reflected back from the user's eyes, as shown anddescribed herein. Once received by the photodetectors 4972, thephotodetectors 4972 may convert the light into electronic signals to beprocessed on the main electronic board 4970 and/or another processingdevice. The plurality of photo detectors may comprise two detectors of abalanced detector pair coupled to the fiber Mach-Zender interferometer,a clock box detector, and a pair of power measurement detectors, forexample.

The main electronic board 4970 may comprise a communication power module4973 (e.g., a Universal Serial Bus, or “USB”) that can communicativelycouple the binocular OCT device 4900 to another processing system,provide power to the binocular OCT device 4900, and/or charge a batteryof the binoculars OCT device 4900. Of course, the binocular OCT device4900 may comprise other modules that may be used to communicateinformation from the binocular OCT device 4900 to another device,including for example, Wi-Fi, Bluetooth, ethernet, FireWire, etc.

The main electronic board 4970 may also comprise VCSEL drivingelectronics 4971 which direct how and when the VCSELs 4952 are to befired towards the user's eyes. Other components on the main electronicboard 4970 comprise an analog block 4974 and a digital block 4975 whichmay be used to process and/or generate analog and digital signals,respectively, being transmitted to the binocular OCT device 4900 (e.g.,from an external processing system), being received from variouscomponents within the binocular OCT device 4900, and/or being receivedfrom various components within the binocular OCT device 4900. Forexample, the peripheral feedback button 4932 may generate an analogsignal that is processed by the analog block 4974 and/or digital clock4975, which may in turn generate a control signal that is used tostimulate the motorized stage module 4942 via the peripheral board 4943.Alternatively, or additionally, the analog block 4974 may process analogsignals from the photodetectors 4972 such that they may be converted todigital signals by the digital block 4975 for subsequent digital signalprocessing (e.g., FFTs, phase wrapping analysis, etc.).

FIG. 6 shows a schematic of an optical configuration 5100 that may beimplemented with the OCT binocular 4900, in accordance with someembodiments. The optical configuration 5100 comprises one or more VCSELs4952 that are fiber coupled via an optical coupler 5126. As discussedabove, the one or more VCSELs 4952 may be swept over a range ofwavelengths when fired. For embodiments with a plurality of VCSELs 4952,the wavelengths may partially overlap a wavelength sweep range ofanother VCSEL 4952 in the plurality so as to increase in overall sweeprange of the VCSELs 4952. In some instances, this overall sweep range iscentered around approximately 850 nm. The laser light from the one ormore VCSELs 4952 is propagated through the fiber coupler 5126 to a fiberoptic line 5127, where another optical coupler 5118 splits a portion ofthe optical energy from the one or more VCSELs 4952 along two differentpaths.

In the first path, approximately 95% of the optical energy is opticallytransferred to another optical coupler 5119 with approximately 5% of theoptical energy being optically transferred to an optical coupler 5120.In the second path, the optical energy is split yet again via an opticalcoupler 5120. In this regard, approximately 75% of the optical energyfrom the optical coupler 5120 is transferred to a phase correctiondetector 5101-1 through an interferometer such as a Fabry Perotinterferometer comprising an etalon. The etalon and detector maycomprise components of an optical clock 5125. The optical clock 5125 maycomprise a single etalon, for example. The etalon may comprisesubstantially parallel flat surfaces and be tilted with respect to apropagation direction of the laser beam. The surfaces may comprisecoated or uncoated surfaces. The material may comprise any suitablelight transmissive material with a suitable thickness. For example, theetalon may comprise a thickness within a range from about 0.25 mm toabout 5 mm, for example within a range from about 0.5 mm to about 4 mm.The reflectance of the etalon surfaces can be within a range from about3% to about 10%. The etalon can be tilted with respect to the laser beampropagation direction, for example tilted at an angle within a rangefrom about 5 degrees to about 12 degrees. The finesse of the etalon canbe within a range from about 0.5 to about 2.0, for example, for examplewithin a range from about 0.5 to 1.0. The etalon may comprise anysuitable material such as an optical glass. The thickness, index ofrefraction, reflectance and tilt angle of the etalon can be configuredto provide a substantially sinusoidal optical signal at the clock boxdetector. The finesse within the range from about 0.5 to 2.0 can providesubstantially sinusoidal detector signals that are well suited for phasecompensation as described herein, although embodiments with higherfinesse values can be effectively utilized.

In some embodiments, the clockbox may comprise a plurality of etalons.The approach can be helpful in embodiments wherein the one or moreVCSELs comprises a plurality of VCSELs, and the plurality of etalonsprovides additional phase and clock signal information. For example, theclockbox may comprise a first etalon and a second etalon arranged sothat light is transmitted sequentially through the first etalon and thenthe second etalon, e.g. a series configuration, which can providefrequency mixing of the clock box signals and decrease the number ofdetectors and associated circuitry used to measure phase of the sweptsource. Alternatively, the plurality of etalons can be arranged in aparallel configuration with a plurality of etalons coupled to aplurality of detectors.

The phase correction detector 5101-1 may use the light signals from theoptical clock 5125 to correct the phase of light reflected from a user'seyes 5109-1 by matching the phases of the one or VCSELs 4952 via phasewrapping of the light from the one or more VCSELs 4952 as describedherein. The remaining 25% of the optical energy from the optical coupler5120 may be optically transferred to a detector 5101-2 for opticalsafety. For instance, the detector 5101-2 may be used to determine howmuch optical energy is being transferred to the user's eye 5109-1 or5109-2, depending on the orientation of the device. If the binocular OCTdevice 4900 determines that the detector 5101-2 is receiving too muchoptical energy that may damage the user's eyes, then the binocular OCTdevice 4900 may operate as a “kill switch” that shuts down the one ormore VCSELs 4952. Alternatively, or additionally, the binocular OCTdevice 4900 may monitor the detector 5101-2 to increase or decrease theoptical energy from the one or more VCSELs 4952 as deemed necessary forlaser safety and/or signal processing. The OCT device may comprise asecond safety detector 5101-3 to provide a redundant measurement forimproved eye safety.

The optical energy transferred to the optical coupler 5119 (e.g.,approximately 95% of the optical energy from the one or more VCSELs4952) is also split along two paths with approximately 99% of theremaining optical energy being optically transferred along a fiber to anoptical coupling element 5122 and with approximately 1% of the remainingoptical energy also being optically transferred to a detector 5101-3 forlaser safety of the binocular OCT device 4900. The portion of theoptical energy transferred to the to the optical coupler 5122 may besplit by the optical coupler 5122 between two optical path loops 5110and 5111 of the Mach-Zender interferometer, approximately 50% each, forexample. The reference optical path loop 5110 may comprise a portion ofthe reference arm of the interferometer and provide a reference opticalsignal for one or more of the AL measurement, the corneal thicknessmeasurement or the retinal thickness measurement of the user's eye5109-1 (e.g., the measurement signal reflected from the user's retinathrough the measurement optical path loop 5111).

In some embodiments, the reference arm comprises a plurality ofreference arms of different distances and corresponding differentoptical path lengths. For example, the reference optical path maycomprise a plurality of optical fibers in a parallel opticalconfiguration to provide a plurality of different optical path lengths.Although reference is made to a parallel configuration one of ordinaryskill in the art will understand that this refers to the couplingarrangement of the fibers, and not necessarily to the orientation alongthe lengths of the fibers, which can be arranged in any suitablenon-parallel configuration, e.g. with loops. In some embodiments, thereference optical path loop 5110 comprises a portion of a firstreference optical path with a first reference optical path length so asmeasure the location of the cornea of the eye. A second referenceoptical path comprises a different reference length. A second referenceoptical path loop 6110 comprises a portion of the second referenceoptical path with the second reference optical path length so to measurea location of the retina of the eye. In some embodiments, the referenceoptical path is split into the first reference optical path with coupler6122, which is coupled to the first reference optical path loop 5110 andthe second optical path loop 6110 in order to split the reference beaminto the first reference beam and the second reference beam. The firstreference beam and the second reference beam may be combined with acoupler 6121 in order to combine the first reference beam and the secondreference beam prior to being combined with the measurement beam withthe coupler 5121. Although reference is made to optical fibers to splitthe reference beam, one of ordinary skill in the art will recognize thatthis can also be done with beam splitters.

The portion of the optical energy transferred through the optical loop5111 is transferred to the user's left eye 5109-1 along the measurementarm of the Mach-Zender interferometer. For instance, the optical energybeing transferred to the user's eye 5109-1 may pass through the OPDcorrection module 4940 to perform any optical path distance correctionsappropriate to the interferometer of the binocular OCT device 4900. Thislight may then be scanned across the user's eye 5109-1 via a scanningmirror 5113 of the scanner module 4990 to measure the retinal thicknessof the user's eye 5109-1 while the user's eye 5109-1 is fixated on afixation target 4912-1 (e.g., along a fixation path 5106-1).

The fixation target 4912-1 can be back illuminated with LED 5102-1, andlight may be propagated along the optical path 5106-1 through opticalelements 5103-1 and 5105-1 and the dichroic mirror 5115, comprising ahot mirror. In some instances, the target of fixation may also includean illumination stop 5104 so as to provide relief to the user's eye5109-1 while fixating on the target.

The light impinging the user's cornea and retina of the eye 5109-1 maybe reflected back along the path established by the OPD correctionmodule 4940, the scanning mirror 5113, the focusing element 5114, thedichroic mirror 5115, and the optical element 4916-1, through theoptical loop 5111, and back to the optical coupler 5122. In thisinstance, the optical coupler 5122 may optically transfer the reflectedoptical energy to an optical coupler 5121 which may couple the reflectedoptical energy from the measurement arm with the reference opticalenergy that was split into the plurality of reference optical pathsalong loops 5110 and loop 6110. The optical coupler 5121 may thenoptically transfer that optical energy to the balanced detector's 5101-4and 5101-5 such that an axial length measurement can be performed. Insome embodiments, the measurement comprises corneal thicknessmeasurement and a retinal thickness measurement. In performing themeasurement with the balanced detector, the optical coupler 5121 maysplit that optical energy to approximately 50% to each of the detectors5101-1 and 5101-4, such that the interference signals arrive out ofphase on the balanced detectors.

The light may be focused through a plurality of optical elements 5112and 5114, being directed to the user's eye 5109-1 via a dichroic mirror5115 and focused on the user's retina via the optical element 4916-1.The light from the scanning mirror 5113 and the light reflected from theuser's eye 5109 are both shown as reflecting off the dichroic mirror5115, which may comprise hot mirror 4913 configured to generally reflectinfrared light and transmit visible light.

As can be seen in this example, the user's right eye 5109-2 does notreceive any optical energy from the one or more VCSELs 4972 with theorientation shown. Rather, the user's right eye 5109-2 is used forbinocular fixation with the target 4912-2, which can be back illuminatedwith another LED 5102-2. The target 4912-2 can be of similar size andshape to target 4912-1 and be presented to the eye with similar optics,so as to provide binuclear fixation. In this regard, the user's righteye 5109-2 may also fixate on the target 4912-2 along an optical path5106-2 through the optical elements 4916-2, 5105-2, 5103-2, and theillumination stop 5104-2, which comprises similar optical power,separation distances and dimensions to the optics along optical path5106-1.

The binocular OCT system 4900 can be configured to move opticalcomponents to a customized configuration for the user being measured.Lens 4916-1 can be adjusted along optical path 5106-1 in accordance withthe refraction, e.g. eyeglass prescription, of the eye being measured.Lens 4916-1 can be moved under computer, user or other control to adjustlens 4916-1 to bring the fixation target 4912-1 into focus and to focusthe measurement beam of the OCT interferometer on the user's retina. Forexample, the lens can be translated as shown with arrow 5146. In someembodiments, lens 4916-1 comprises an objective lens, e.g. a lens alongthe optical path closest to the corresponding eye. Lens 4916-2 can bemoved under computer, user or other control to adjust lens 4916-2 tobring the fixation target 4912-2 into focus on the user's retina. Forexample, the lens can be translated as shown with arrow 5144. In someembodiments, lens 4916-2 comprises an objective lens, e.g. a lens alongthe optical path closest to the corresponding eye. The OPD correctionmodule 4940 can be translated axially toward and away from mirror 5113as shown with arrows 5146. The OPD correction module 4940 can be movedunder computer control to appropriately position the optical pathdifference between the measurement arm and the reference arm for theuser's eye being measured. The interpupillary distance can be adjustedby translating the optical path 5106-2 toward and away from optical path5106-1.

The free space optics module 4910-2 may comprise one or more componentsalong optical path 5106-2, such as the LED 5101-2, the fixation target4912-2, lens 5103-2, aperture 5104-2, lens 5105-2, or lens 4916-2. Thefree space optics module 4910-2 can be translated laterally toward andaway from the optical components located along optical path 5106-1 toadjust the inter pupillary distance as shown with arrow 5142. The freespace retinal thickness optics module 4910-1 may comprise one or morecomponents located along optical path 5106-1, such as the LED 5102-1,the fixation target 5103-1, the aperture 5104-1, the mirror 5116, thelens 5105-1, the mirror 5115, or lens 4916-1. The OPD correction module5146 may comprise the optical fiber of the measurement arm of theinterferometer, and lens 5112 to substantially collimate light from theoptical fiber and to focus light from the retina into the optical fiber.

FIG. 7 shows a block diagram of the optical configuration 5100configured on an optical layout board 5150, in accordance with someembodiments. For example, the binocular OCT device 4900 may beconfigured with a plurality of layers extending approximately alongplanes, each of which layers may be configured to perform a particularfunction. In this instance, the optical layout board 5150 provides asupport for the optical configuration 5100, which can be used todecrease vibrations of the optical components. The optical board 5150may comprise a plurality of components enclosed within a housing of afiber optics module as described herein. The plurality of componentsenclosed within the housing 5153 and supported on the board, maycomprise one or more of coupler 5118, coupler 5119, coupler 5120,coupler 5121, coupler 5122, reference arm comprising optical fiber 5110,and any combination thereof. The one or more VCSELs 4952 may be enclosedwithin the housing. The plurality of optical fibers extending fromcoupler 5120 can extend through the housing to the appropriate detector,for example to couple to clock box detector 5101-1 and safety detector5101-2. The optical fiber extending from coupler 5119 can be coupled toa second safety detector 5101-3 and extend though housing 5153. A secondoptical fiber extending from coupler 5119 can be coupled to theinterferometer to measure the sample with optical coupler 5122. Theoptical fiber portion of the sample measurement arm may extend fromcoupler 5122 and through the housing 5153 to the optical path differencecorrection module 4940, for example.

The printed circuit board may provide a support layer extending along anelectronics plane in which some processing devices (e.g., the mainelectronic board 4970 including the driving electronics 4971) couldcouple to the optical layout board 5150 through a cable 5151 thatconnects to a connector 5152 configured with the optical layout board5150 in order to drive one or more VCSELs 4952.

FIG. 8 shows a perspective view of a modular embodiment of the binocularOCT 4900, in accordance with some embodiments. For instance, the mainelectronic board 4970 of the binocular OCT 4900 may be implemented as aprinted circuit board (PCB) 5160 that is mounted to a housing 4953enclosing optical components on the optical layout board 5150. The PCB5160 may provide the power and electronics to control the opticalconfiguration 5100 of the optical layout board 5150. The PCB 5160 mayalso include or be communicatively coupled to peripheral boards 4932-1,4932-2, 4943, 4914-1, and 4914-2. The binocular OCT device 4900 may alsocomprise free space optics modules that are mounted on the opticallayout board 5150 and communicatively couple to the main electronicboard 4970. The free space optics modules mounted on the optics boardmay comprise one or more of module 4910-1, module 4910-2, or OPDcorrection module 4940 as described herein. The free space module 4910-2can be configured to move in relation to optical layout board 5150 toadjust the inter pupillary distance. The OPD correction module can beconfigured to move relative to optical layout board 5150.

The interferometer module 4950 may comprise the couplers of the opticalfibers as descried herein and the one or more VCSELs 4952. The mainelectronic board 4970 or one of the peripheral boards may comprise theelectronics that drive the VCSELs 4952. The one or more VCSELs 4952being optically coupled to the optical fibers on the optical layoutboard 5150, propagate laser light to the optical fibers on the opticallayout board 5150. The laser light reflected from the user's eye 4910-1can be propagated to the PCB 5160 where the photodetector 4972 detectsthe reflected laser light and converts the light to an electronic analogsignal for processing by the analog block 4974.

In some embodiments, the optical layout board 5150 provides damping tothe binocular OCT 4900. For instance, if the binocular OCT 4900 were tobe dropped, a damping mechanism configured with the optical layout board5150 may compensate for any oscillatory effects on impact of thebinocular OCT 4900 and protect the components thereof (e.g., the opticallayout board 5150, the PCB 5160, interferometer module 4950, and thecomponents of each). The mounting plate 5150 may comprise similardamping mechanisms.

FIG. 9 shows a perspective/cut-away view of the binocular OCT 4900, inaccordance with some embodiments. In this view, the optical layout board5150, the PCB 5160, and the interferometer module 4950 are mechanicallycoupled together in a compact form configured within the housing 4903 ofthe binocular OCT 4900. As can be seen in this view, the fixationtargets 4912-1 and 4912-2 (e.g., LED light) are visible to the userthrough the lenses 4916-1 and 4916-2, respectively, when the user placesthe binocular OCT 4900 proximate to the user's eyes. Laser light fromthe VCSELs propagates along a portion of the same optical path as thefixation target 4912-1. Thus, when the user gazes on the fixationtargets 4912-1 and 4912-2, the laser light from the one or more VCSELsas described herein are operable to propagate through the user's eye andreflect back to the optical layout board 5150 for subsequent processingto determine the user's retinal thickness.

FIG. 10 shows another perspective/cut-away view of the binocular OCTdevice 4900, in accordance with some embodiments. In this view, theoptical layout board 5150 is illustrated to show the configuration ofthe one or more VCSELs 4952, the fiber coupler 5126, the detector's5105-1-5105-5, the Fabry Perot optical clock 5125, and the opticalcouplers 5118-5122. The optical layout board 5150 may also comprisesplices 5170.

FIG. 11 shows the binocular OCT system 4900 comprising an eye positionsensor, in accordance with some embodiments. FIG. 11 shows anoverhead/cut-away view of the binocular OCT 4900 comprising an eyeposition sensor 5610, in accordance with some embodiments. The eyeposition sensor 5610 may comprise one or more of an array sensor, alinear array sensor, a one dimensional array sensor, a two-dimensionalarray sensor, a complementary metal oxide (CMOS) two-dimensional arraysensor array sensor, a quadrant detector or a position sensitivedetector. The eye position sensor 5610 can be combined with a lens toform an image of the eye on the sensor, such as a Purkinje image from areflection of light from the cornea of the eye. The eye position sensorcan be incorporated into any of the embodiments disclosed herein, suchas the binocular OCT system described with reference to FIGS. 1B to 10.

In the view shown, the optical configuration 5100 is mounted on theoptical layout board 5150 above the fiber-optic couplings (e.g., thefiber loops 5110 and 5111 of FIG. 6) and the optical couplers 5118-5122,and other fiber components as described herein. Thus, the one or morefree space optical components as described herein may be opticallycoupled to the fiber components thereunder.

As shown, the free space optics modules 4910-1 and 4910-2 are generallyaligned with the user's eyes 5109-1 and 5109-2, respectively. Thedistance between the free space optics modules 4910-1 and 4910-2 may beadjusted according to the user's IPD as described herein. In someembodiments, this adjustment is maintained for the user while thebinocular OCT 4900 is in the user's possession. For example, the usermay be a patient using the binocular OCT 4900 for home use over a periodof time. So as to ensure that a correct axial length, corneal thicknessand retinal thickness measurements are performed while in the user'spossession, the binocular OCT 4900 may prevent the user from adjustingthe IPD. Similarly, the binocular OCT 4900 may also prevent the userfrom adjusting the OPD via the OPD correction module 4940.

As can be seen in this view (FIG. 11), the fixation targets 4912-1 and4912-2 (e.g., LED light targets) pass through various optical elementsof their respective free space optics modules 4910-1 and 4910-2. The OPDcorrection module 4940 receives the laser light from the one or moreVCSELs 4952 and directs light toward the scanning mirror 4990 asdescribed herein. Light from the scanning mirror 4990 passes through alens and is reflected by a dichroic mirror 5115 to the user's eye 5109-1through the lens 4916-1.

In some embodiments, the OCT measurement beam remains substantiallyfixed relative to the position sensor at each of the plurality ofpositions of the fixation target.

In some embodiments, the axial length map comprises a plurality ofregions corresponding to the plurality of positions of the fixationtarget.

In some embodiments, the axial length map comprises from 5 to 20 regionsand the plurality of locations of the fixation target comprises from 5to 20 regions.

In some embodiments, the OCT system comprises a scanner to scan the OCTbeam to a plurality of positions on a patient's retina for each of theplurality of positions of the fixation target. For example, the scannercan be configured to scan an area of the retina with the plurality ofretinal positions for each of the plurality of fixation targetpositions, and the area of the cornea and retina scanned with each ofthe plurality of fixation target positions is less than an area of theone or more of axial length map, the retinal image, or the cornealimage.

In some embodiments, the OCT measurement beam is transmitted to thescanning mirror mounted on a piezo driven motor in order to compensatefor the optical path distance. For example, the hot mirror configured toreflect the OCT measurement beam and transmit the fixation target can beconfigured to translate in order to adjust the optical path differencewhile the position of the XYZ translation stage remains substantiallyfixed. In some embodiments, the translation of the mirror will reflectthe OCT measurement beam to adjust the OPD while the path of thetransmitted light remains substantially unaltered, such as the path ofthe light from the fixation target and optionally light transmittedthrough the mirror to the position sensor.

In some embodiments, the OCT beam is routed through amicromirror/microlens assembly, in which both direction and OPD can beadjusted. In some embodiments, the beam radius may also be varied. Themicro-optics assembly may be mounted on a set of linear drives,including piezo drives with submicron resolution. Such drives arecommercially available from DTI motors as described on the Internet atdtimotors.com.

Such a system may rely on a decreased driving force, so that a drivingforce of 1N may be sufficient, in accordance with some embodiments.

In some embodiments the driving force is within a range from 0.5 Newtons(N) to 2.5 N, and a resolution does not exceed 0.5 microns. In someembodiments, the response time is 1 mm per 0.1 sec or faster. This lensassembly can be controlled with a processor such as a microcontroller oran FPGA, so as to increase the signal-to-noise ratio as describedherein. In some embodiments, the lens assembly is configured to ditherthe OCT measurement beam on the retina.

As described, the disclosed OCT system includes a scanner that can becontrolled to cause a measurement beam to move in a scan pattern on apatient's cornea and retina. The scan pattern may be one of varioustypes, including a stop and go scan pattern, a star scan pattern, acontinuous scan pattern, a Lissajous scan pattern, or a flower pattern,sometimes referred to as a rose curve. The flower pattern or rose curvemay be used to generate measurement data that can be processed togenerate data that represents data that would be obtained from adifferent scan pattern. Further, the flower pattern or rose curve may beused to generate measurement data that can be processed to generateinterferometric data that improves the ability to detect fluid orpockets of fluid in regions of the retina.

FIG. 12 shows an OCT device 4900 with a plurality of reference arms,e.g. two reference arms, in accordance with some embodiments. The OCTdevice comprises a light source such as one or more VCSELs 4952. Thelight source may comprise any suitable light source such as broadbandsource, a super luminescent diode (SLD), a single VCSEL, a MEMS basedVCSEL, a plurality of VCSELs, a plurality VCSELs without MEMS mirrors inwhich wavelength is swept with overdriving of the VCSEL, an array ofVCSELs, or an array of MEMS VCSELs. The OCT device may comprise aplurality of reference optical paths, such as a first reference opticalpath of a first reference arm to measure a position of the cornea, and asecond reference optical path of a second reference arm to measure aposition of the retina. The first reference optical path may comprise afirst loop 5110 along the first reference optical path and a second loop6110 along the second reference optical path as described herein. TheOCT system may comprise a plurality of couplers to couple optical fibersas described herein. The first and second reference optical paths allowsimultaneous measurements of the positions of the retina and cornea asdescribe herein. The measurement optical path 1210 along a measurementarm of the OCT system may comprise a measurement optical path loop 1211.The portion of the measurement path 1210 extending into the eye maycomprise measurement beam 1212.

The light from the reference paths 1220 and the measurement path 1210can be combined in many ways. In some embodiments, a coupler 6122 splitsthe reference optical path into the first reference optical path and thesecond reference optical path, and a coupler 6121 combines the tworeference optical paths. A coupler 5121 combines the reference opticalpath and the measurement optical path, and a plurality of couplersextends from coupler 5121 to balanced detectors 5104-4 and 5104-5 asdescribed herein.

In some embodiments, the OCT device is configured to measure axiallength at one location along the eye, for example with a single OCTmeasurement beam configured to scan the eye without moving a scanningmirror. Alternatively, the OCT system can be configured to scan themeasurement beam along the eye as described herein.

In some embodiments, the OCT system is configured to measure the axiallength of the eye with a plurality of optical fibers arranged in asubstantially fixed configuration. Each of the plurality of opticalfibers can be configured to scan a first location of the cornea and asecond location of the retina. For example, the OCT device 4900 maycomprise a plurality of light sources, interferometers, and detectors,in which the configuration shown in FIG. 12 is duplicated for each ofthe plurality of measurement beams. In some embodiments, the one or morelight sources 4952 comprises an array of VCSELS coupled to a pluralityof optical fibers and couplers and detectors, each of which is similarto the configuration of FIG. 12.

FIG. 13A shows signal intensity and frequency for an OCT device with twosignals simultaneously received with one or more detectors, e.g. abalanced pair, in accordance with some embodiments. In some embodiments,the frequencies of the interference signal is related to the opticalpath difference between the reference arm and the sample location alongthe measurement arm. In some embodiments, the zero optical pathdifference location is set to a suitable position between the cornea andlens to generate two different frequency bands for the cornea and lens.By positioning the zero optical path difference location such that thedistance to the cornea and the distance to the retina are different, twodifferent distributions of frequencies can be obtained, for example witha single reference arm optical path. By positioning the zero opticalpath difference location closer to the cornea and farther from theretina, the two distributions of frequencies will comprise first lowerfrequencies corresponding to the position of the cornea at a firstlocation along the measurement optical path and second higherfrequencies corresponding to the position of the retina at a secondlocation along the measurement optical path. In some embodiments, afirst peak 1310 can occur for a first distribution of frequencies, whichcorrespond to the first optical path difference along the samplemeasurement arm, e.g. corneal frequencies, and a second peak 1320 canoccur for a second distribution of frequencies, which correspond to thesecond optical path difference along the sample measurement arm, e.g.retinal frequencies. Alternatively, the optical path difference for thecornea can be greater than the retina, such that the corneal frequenciesare greater than the retinal frequencies. These signals can be generatedwith the OCT system comprising a single reference arm or a plurality ofreference arms as described herein, for example with reference to FIGS.6 and 12. In some embodiments, the optical path differences for thecornea and retina are sufficiently different so to provide separation ofthe distribution of frequencies of the first peak 1310 and thedistribution of frequencies of the second peak 1320. In someembodiments, the first reference fiber comprises a first lengthconfigured to provide first measurement frequencies for the cornea andthe second reference optical fiber comprises a second length configuredto provide a second measurement frequencies for retina, in which thefirst frequencies are resolvable from the second frequencies.

FIG. 13B shows signal frequency broadening of a distribution offrequencies 1330 due to chirp of the swept source. In some embodiments,the swept source VCSEL is driven with a non-linear current ramp tonarrow the distribution of frequencies 1330 toward an ideal distribution1340 comprising a narrower distribution of frequencies. This approach iswell suited for use with VCSELs that rely on increased heat fromoverdriving of the current to the VCSEL to sweep the wavelength of theVCSEL.

In some embodiments, the reference arms have different polarizations inorder to separate the signals. This has the advantage of decreasinginterference between the reference signals.

In some embodiments, one or more lenses, e.g. the objective lens closestto the eye, comprises a bifocal configuration to focus lightsimultaneously on the retina and the cornea in order to increase theoptical signal.

FIG. 14 shows measurement depth of an axial length monitor, inaccordance with some embodiments. In some embodiments, the axial lengthmonitor comprises a measurement depth that is greater than utilized forretinal measurements. In some embodiments, which measure retinalthickness, the measurement depth is within a range of approximately 8 to10 mm. The axial length monitor can be configured to measure a suitabledistance corresponding to the axial length of the eye, which cancorrespond to a range from about 29 mm to about 34 mm in air. Thecoherence length of the light source can be sufficiently long to provideinterference of the light source as described herein. In someembodiments, the location of the zero optical path difference 1430 islocated between the cornea and the retina, for example between the lensand retina, when the eye is aligned with the OCT measurement system tosimultaneously measure the cornea and retina. In some embodiments, themeasurement beam 1212 is focused to a waist near the zero OPD location,for example within about 1 mm of the zero OPD location. Alternatively, abifocal lens can be used to focus the measurement beam on the retina andcornea. A first distance 1410 between the zero optical path difference1430 and the cornea is measured, and a second distance 1420 between thezero optical path difference (“OPD”) between the cornea and retina aremeasured simultaneously in response to the generated frequencies asdescribed herein. This approach has the benefit of decreasing themeasurement depth used to perform the measurement, for example bydecreasing the coherence length and number of sampling points used foreach A-scan wavelength sweep of the measurement beam. In someembodiments, the first distance 1410 and the second distance 1420correspond to non-overlapping mirrored interference terms, in which boththe corneal surface and retinal surface appear in the image at differentdistances corresponding to distances from the zero OPD position. In someembodiments, the non-overlapping mirrored interference terms allow eachA-scan to be obtained with fewer sampling points as compared tonon-mirrored interference terms.

In some embodiments, the reference optical paths are adjusted to set afirst zero OPD for the first reference optical path at a first locationcorresponding to first frequencies from the cornea, and to set thesecond zero OPD for the second reference optical path at a secondlocation corresponding second frequencies from the retina, in which thefirst frequencies differ from the second frequencies to be separatelyresolved. The combined simultaneously generated signals can be separatedbased on frequencies of the corresponding the reference optical pathdifferences as described herein. This approach can decrease sampling andcoherence length of the OCT system to simultaneously measure positionsof the cornea and retina.

In some embodiments, the characteristics of interference signals fromthe cornea differ from the characteristics of interference signals fromthe retina, and the differences in these characteristics can be used todetermine which frequencies correspond to the cornea and whichfrequencies correspond to the retina. These characteristics may compriseone or more of interference signal intensity or peak sharpness of adistribution of frequencies, for example. In some embodiments, ananterior surface of the cornea provides an interference signal withstronger intensities and a sharper peak of the distribution offrequencies than the intensity and distribution of frequencies fromsurfaces of the retina, for example.

The measurement beam 1212 can be focused in any suitable manner tomeasure the cornea and retina and provide measurement signals from thecornea and retina. For example, the measurement beam can be focusedbetween the cornea and retina. Alternatively or in combination, themeasurement beam can be focused with a variable lens that changes focusof the measurement beam between the cornea and retina, for example withsequential activation of a lens to a first configuration to focus themeasurement beam on the cornea and to a second configuration to focusthe measurement beam on the retina. A multi focal lens such as a bifocallens or a diffractive lens can be used to simultaneously focus the beamon the cornea and retina. In some embodiments, the lens simultaneouslyfocuses on the measurement beam on the cornea and retina and thereference arm comprises the plurality of reference paths as describedherein.

Physical Measurement Considerations.

-   -   a. The measurement depth in a swept-source OCT is related to        following aspects:        -   i. Coherent length of the light source;        -   ii. Sampling points per wavelength sweep range; and    -   b. In case of Retinal Thickness Measurement System: (ii) can be        a limiting factor

Methods to Increase Measurement Depth

a. Increase sampling points per wavelength sweep range by either:

-   -   i. Increasing sampling rate (at constant wavelength sweep rate);        or    -   ii. Decrease wavelength sweep rate (at constant sampling rate).

In some embodiments, the OCT system is configured to switch betweenmeasurement configurations to measure two or more of the following:axial length by measuring the distance between the corneal and theretinal surfaces; retinal thickness; or corneal thickness. In someembodiments, the processor comprises instructions to switch among axiallength measurements, retinal thickness measurements, and cornealthickness measurements. Tables 2 and 3 describe measurement parametersthat can be used for retinal thickness measurements or axial lengthmeasurements, and the processor can be configured to switch among thesemeasurement configurations. Although reference is made to an OCT systemthat can switch between configurations axial length and retinalthickness configurations, in some embodiments the OCT measurement systemis configured to measure axial length without being configured to switchto a retinal thickness measurement configuration.

Table 2 shows measurement parameters for a retinal thickness measurementsystem configuration and an axial length measurement systemconfiguration. Although approximate parameters are shown in Tables 2 and3, these values can be decreased by 50% or increased by 100% or morefrom the values shown, to perform the appropriate measurement. Forexample, Table 2 shows that by increasing the sampling frequency of from20 MHz to 80 MHz, the number of sampling points per A-scan from 1000 toapproximately 4000, to perform axial length measurements as describedherein.

TABLE 2 Measurement Parameters- Approximate Dimensioning for IncreasedSampling Frequency. Retinal Thickness Axial Length Parameter MeasurementSystem Measurement System A-scan repetition rate 10 kHz 10 kHz Durationof A-scan 50 μs 50 μs Break between A-scans 50 μs 50 μs Number ofsampling 1000 ~4000 points per A-scan Sampling frequency 20 MHz 80 MHzTotal acquisition duration 2 s 2 s Total number of A-scans 20,000 20,000Scan area on retina 2 × 2 mm² On-axis only or scanned

Table 3 shows parameters that can be used for measuring retinalthickness and for measuring axial length by using a decreased wavelengthsweep rate. In some embodiments, each wavelength sweep corresponds toone A-scan measurement. The duration of a sweep can be increased inaccordance with a decrease in the rate of sweeping, to increase thenumber of sampling points per A-scan. Although the A-scan repetitionrate is decreased, the number of A-scan sampling points increasesproportionally for a fixed sampling frequency, e.g. 20 MHz. In someembodiments, the measured length along the optical path of themeasurement beam, e.g. along the A-scan, is proportional to the numberof sampling points per A-scan, such that the measured length of theA-scan along the measurement optical path increases proportionally.

TABLE 3 Approximate Dimensioning for Decreased λ Sweep Rate. ApproximateValue for Retinal Thickness Axial Length Parameter Measurement SystemMeasurement A-scan repetition rate 10 kHz 2.5 kHz Duration of A-scan 50μs 200 μs Break between A-scans 50 μs 200 μs Number of sampling 1000~4000 points per A-scan Sampling frequency 20 MHz 20 MHz Totalacquisition duration 2 s 2 s Total number of A-scans 20,000 5,000 Scanarea on retina 2 × 2 mm² On-axis only or scanned

In some embodiments, the retina position is detected by OCT measurement.

In some embodiments, the cornea position is detected by a positionsensor such as 1^(st) Purkinje reflection measurement as describedherein.

Both measurements can be approximately simultaneous, e.g. within 100 ms,to decrease measurement inaccuracy related to motion, for example.

FIG. 15 shows a fixation target 1500 configured to change color inresponse to user alignment to provide feedback to the user, inaccordance with some embodiments. The fixation target 1500 comprises anouter zone such as ring 1510 to indicate coarse alignment and an innerzone such as central dot 1520 to indicate fine alignment. The outer zonemay comprise a first color, e.g. red, when the eye is not coarselyaligned with the measurement system and a second color, e.g. green, whenthe eye is coarsely aligned with the measurement system. The alignmentof the eye with the measurement system can be measured in many ways, forexample by measuring a position of the eye as described herein. Thefixation target 1500 may comprise a first configuration 1500-1 in whichthe outer zone comprising ring 1510 and inner zone comprising centraldot 1520 each comprises a first color such as red to indicate no coarsealignment and no fine alignment. The fixation target 1500 may comprise asecond configuration 1500-2 to indicate coarse alignment and no finealignment. In the second configuration, the outer zone may comprise asecond color such as green to indicate the coarse alignment and theinner zone comprises a first color such as red to indicate a lack offine alignment. A third configuration 1500-3 of the fixation target 1500may indicate coarse alignment and fine alignment conditions have beenmet. In the third configuration, the outer zone and the inner zone eachcomprises the second color, e.g. green. The user can self-align with thesystem in response to the colors of the fixation target. In someembodiments, once the user is aligned with the OCT measurement system asindicated with third configuration 1500-3, the OCT system willautomatically measure the axial length of the eye as described herein.

The fixation target can also be used to provide device statusinformation to the user, for example by blinking or providing othercolors. Alternatively or in combination, the OCT system may comprise oneor more external indicator lights to provide the device statusinformation. The battery status information indicated by the one or moreexternal indicator lights may comprise one or more of battery status,alignment status, or device status. The battery status information maycomprise one or more of charged, currently charging, or low batterylevel. The alignment status provided by the one or more external lightsmay comprise not aligned, coarsely aligned, or fine alignment, similarlyto the fixation light. The device status provided by the one or morelights may comprise one or more of ready to use, successful acquisition,processing data, or error.

Although reference is made to fixation target to indicate alignment,other approaches can be used, such as one or more of a visual display,voice feedback or voice acquisition.

FIG. 16 shows a system 1600 comprising a VCSEL array 1605 coupled to aplurality of optical fibers 1610 to measure axial thickness at aplurality of corneal and retinal locations. The plurality of opticalfibers 1610 is coupled to a second plurality of optical fibers 1630comprising distal ends arranged in a pattern to measure the cornea andretina at a plurality of locations as described herein. The plurality ofoptical fibers 1630 comprises a portion of the measurement arm 1210. Thedistal ends of the optical fibers 1630 are oriented toward one or morelenses 1670, which focus light from the ends of the optical fibers at aplurality of locations within the eye. In some embodiments, theplurality of corneal and retinal locations is measured without ascanning mirror to scan the beam to the plurality of locations. Thelight from the retina is focused back into the ends of the opticalfibers through lens 1670. The lens 1670 may comprise a mono focal lens,a variable lens, a multifocal or a bifocal lens to focus light betweenthe cornea and retina, on the retina, or on the cornea as describedherein.

The plurality of optical fibers 1610 is coupled to the plurality ofmeasurement optical fibers 1630 with a plurality of couplers 1620. Theplurality of couplers 1620 receives light from the VCSEL array 1605 andsplits the light from the VCSEL array into the optical fibers 1630 ofthe measurement path and the optical fibers 1640 of the reference path.The reference path comprises a plurality of reference path opticalfibers 1645, which may comprise a plurality of split reference paths, inwhich each of the split reference paths comprises a first distancecorresponding to the cornea and a second distance corresponding to theretina as described herein. The plurality of reference path opticalfibers comprises a plurality of reference path output optical fibers1647.

The light from the plurality of reference optical fibers and theplurality of measurement optical fibers is combined with a plurality ofcouplers 1650 and directed to a plurality of detectors 1660, such as aplurality of balanced detectors as described herein. In someembodiments, the plurality of measurement path optical fibers comprisesoptical fibers 1635 extending from the plurality of couplers 1620 to theplurality of couplers 1650. The output light from the plurality ofcouplers 1650 comprises a plurality of interference signals resultingfrom combination of light from the plurality of measurement path opticalfibers 1635 and the plurality of reference path output optical fibers1647. The light from the plurality of couplers 1650 that is directed tothe plurality of plurality of detectors 1660 comprises interferencesignals in response to sweeping of VCSEL wavelength and can be processedto determine the locations of the cornea and the retina as describedherein.

The VCSEL array can be coupled to the optical fibers and detector togenerate interference signals in any suitable way. In some embodiments,the VCSEL array comprises one or more light sources 4952 as describedherein. The one or more light sources 4952 may comprise an array ofVCSELs comprising a first VCSEL 4952-1, a second VCSEL 4952-2, a thirdVCSEL 4952-3 up to an Nth VCSEL 4952-N. The plurality of optical fibers1610 may comprise any suitable number of optical fibers, such as a firstoptical fiber 1610-1, a second optical fiber 1610-2, a third opticalfiber 1610-3, up an Nth optical fiber 1610-N. The plurality of couplers1620 coupled to the plurality of optical fibers 1610 may comprise anysuitable number of couplers, such as a first coupler 1610-1, a secondcoupler 1610-2, a third coupler 1610-3, up to an Nth coupler 1610-N.

The measurement optical path 1210 can be configured in any suitable way.In some embodiments, the measurement optical path 1210 comprises firstmeasurement optical fibers 1630 and second measurement optical fibers1635 with the plurality of connectors 1620 coupling the measurementoptical fibers. In some embodiments, the first measurement opticalfibers comprise a first optical fiber 1630-1, a second optical fiber1630-2, a third optical fiber 1630-3, up to an Nth optical fiber 1630-N.The second plurality of measurement optical fibers 1635 comprisesoptical fibers coupled to each of the measurement optical fibers 1630with the plurality of couplers 1620. The plurality of couplers 1620 maycomprise a first coupler 1620-1, a second coupler 1620-2, a thirdcoupler 1620-3, up to an Nth coupler 1620-N.

The number of element up to N as described herein may comprise anysuitable number, and N may comprise, 10, 20, 50, 100 or 200, or moreelements.

The plurality of reference path optical fibers 1645 and the plurality ofcouplers 1650 can be configured in any suitable way in accordance withthe present disclosure. In some embodiments, the plurality of referencepath optical fibers 1645 comprises 2N reference paths, for example whenthe reference path comprises a first distance corresponding to thecornea and a second difference corresponding to the retina, e.g. Nreference paths with the first distance and N reference paths with thesecond distance. Alternatively, the plurality of reference path opticalfibers 1645 may comprise N optical fibers, e.g. comprises the pluralityof reference optical fibers 1640, and the plurality of output opticalfibers 1647 comprises the plurality of reference path optical fibers1640. In some embodiments, the plurality of couplers 1650 comprise Ncouplers, in which each of the plurality of couplers is coupled to oneof the plurality of output reference optical fibers 1647 and one of theplurality of measurement optical fibers 1635.

FIG. 17 shows a system 1700 comprising the VCSEL array 1605 imaged intothe eye with one or more lenses 1670, and a light received from the eyeimaged onto a detector array with one or more lenses after beingcombined with a reference beam, for example with a Mach-Zenderconfiguration. Light from the VCSEL array 1605 is directed toward one ormore lenses 1730, which may substantially collimate light from theplurality of VCSELs. The light from one or more lenses 1730 is directedtoward a beam splitter 1760. The beam splitter 1760 reflects a portionof the light along a reference optical path and transmits a secondportion of the light along a measurement optical path. The beam splitter1760 may comprise any suitable beam splitter such as a partiallyreflective mirror or a polarizing beam splitter for example. A firstportion of the light from the beam splitter 1760 is directed toward amirror 1740 along a reference optical path. Light reflected from mirror1740 is directed toward beam splitter 1740 and transmitted through thebeam splitter 1760 toward detector 1710, which may comprise an arraydetector such as a complementary metal oxide semiconductor (CMOS) arrayor a charge coupled device (CCD) array, for example. In someembodiments, one or more lenses 1750 is located between the beamsplitter 1760 and mirror 1740.

The portion of light transmitted through beam splitter 1760 is directedalong the measurement optical path toward lens 1780 and the eye. Thelens 1780 may comprise one or more of a variable focus lens, amultifocal lens, or a bifocal lens, for example. The light transmittedthrough mirror is imaged inside the eye to form an image of the VCSELarray 1605 within the eye with the optical power of the eye and the lens1780.

Light returned from the retina is transmitted through lens 1780 andreflected from mirror 1760 toward lens 1720 and detector 1710. The lightreflected from mirror 1760 is transmitted through lens 1720 to form animage of the light from the eye on the detector array. In someembodiments, the image of the detector array formed inside the eye isimaged onto the detector array 1710 with lens 1720, such that the imageof the VCSEL array is imaged onto the detector. As each of the VCSELs ofthe array varies the wavelength, the intensity of the correspondingimage varies and is captured with detector 1710. Detector 1710 iscoupled to a processor and the intensity signal for each VCSEL iscaptured and processed as described herein.

As described herein, the computing devices and systems described and/orillustrated herein broadly represent any type or form of computingdevice or system capable of executing computer-readable instructions,such as those contained within the modules described herein. In theirmost basic configuration, these computing device(s) may each comprise atleast one memory device and at least one physical processor.

The term “memory” or “memory device,” as used herein, generallyrepresents any type or form of volatile or non-volatile storage deviceor medium capable of storing data and/or computer-readable instructions.In one example, a memory device may store, load, and/or maintain one ormore of the modules described herein. Examples of memory devicescomprise, without limitation, Random Access Memory (RAM), Read OnlyMemory (ROM), flash memory, Hard Disk Drives (HDDs), Solid-State Drives(SSDs), optical disk drives, caches, variations or combinations of oneor more of the same, or any other suitable storage memory.

In addition, the term “processor” or “physical processor,” as usedherein, generally refers to any type or form of hardware-implementedprocessing unit capable of interpreting and/or executingcomputer-readable instructions. In one example, a physical processor mayaccess and/or modify one or more modules stored in the above-describedmemory device. Examples of physical processors comprise, withoutlimitation, microprocessors, microcontrollers, Central Processing Units(CPUs), Field-Programmable Gate Arrays (FPGAs) that implement softcoreprocessors, Application-Specific Integrated Circuits (ASICs), portionsof one or more of the same, variations or combinations of one or more ofthe same, or any other suitable physical processor. The processor maycomprise a distributed processor system, e.g. running parallelprocessors, or a remote processor such as a server, and combinationsthereof.

Although illustrated as separate elements, the method steps describedand/or illustrated herein may represent portions of a singleapplication. In addition, in some embodiments one or more of these stepsmay represent or correspond to one or more software applications orprograms that, when executed by a computing device, may cause thecomputing device to perform one or more tasks, such as the method step.

In addition, one or more of the devices described herein may transformdata, physical devices, and/or representations of physical devices fromone form to another. Additionally or alternatively, one or more of themodules recited herein may transform a processor, volatile memory,non-volatile memory, and/or any other portion of a physical computingdevice from one form of computing device to another form of computingdevice by executing on the computing device, storing data on thecomputing device, and/or otherwise interacting with the computingdevice.

The term “computer-readable medium,” as used herein, generally refers toany form of device, carrier, or medium capable of storing or carryingcomputer-readable instructions. Examples of computer-readable mediacomprise, without limitation, transmission-type media, such as carrierwaves, and non-transitory-type media, such as magnetic-storage media(e.g., hard disk drives, tape drives, and floppy disks), optical-storagemedia (e.g., Compact Disks (CDs), Digital Video Disks (DVDs), andBLU-RAY disks), electronic-storage media (e.g., solid-state drives andflash media), and other distribution systems.

A person of ordinary skill in the art will recognize that any process ormethod disclosed herein can be modified in many ways. The processparameters and sequence of the steps described and/or illustrated hereinare given by way of example only and can be varied as desired. Forexample, while the steps illustrated and/or described herein may beshown or discussed in a particular order, these steps do not necessarilyneed to be performed in the order illustrated or discussed.

The various exemplary methods described and/or illustrated herein mayalso omit one or more of the steps described or illustrated herein orcomprise additional steps in addition to those disclosed. Further, astep of any method as disclosed herein can be combined with any one ormore steps of any other method as disclosed herein.

The processor as described herein can be configured to perform one ormore steps of any method disclosed herein. Alternatively or incombination, the processor can be configured to combine one or moresteps of one or more methods as disclosed herein.

Unless otherwise noted, the terms “connected to” and “coupled to” (andtheir derivatives), as used in the specification and claims, are to beconstrued as permitting both direct and indirect (i.e., via otherelements or components) connection. In addition, the terms “a” or “an,”as used in the specification and claims, are to be construed as meaning“at least one of” Finally, for ease of use, the terms “including” and“having” (and their derivatives), as used in the specification andclaims, are interchangeable with and shall have the same meaning as theword “comprising.

The processor as disclosed herein can be configured with instructions toperform any one or more steps of any method as disclosed herein.

It will be understood that although the terms “first,” “second,”“third”, etc. may be used herein to describe various layers, elements,components, regions or sections without referring to any particularorder or sequence of events. These terms are merely used to distinguishone layer, element, component, region or section from another layer,element, component, region or section. A first layer, element,component, region or section as described herein could be referred to asa second layer, element, component, region or section without departingfrom the teachings of the present disclosure.

As used herein, the term “or” is used inclusively to refer items in thealternative and in combination.

The present disclosure includes the following numbered clauses.

Clause 1. A method of measuring a change in a refractive error of aneye, the method comprising: measuring a first axial length of the eyefrom a first zone of a retina at a first time to determine a first axiallength of the eye, the first zone comprising a first maximum distanceacross within a first range from about 0.05 mm to about 2 mm; measuringa second axial length of the eye from a second zone of the retina at asecond time to determine a second length of the eye at a second time,the second zone comprising a second maximum distance across within arange from about 0.05 mm to about 2.0 mm; wherein the change inrefractive error corresponds to a difference between the first axiallength and the second axial length.

Clause 2. The method of clause 1, wherein the first maximum distanceacross is within a range from about 0.1 mm to about 1.5 mm and thesecond maximum distance across is within a range from about 0.1 mm toabout 1.5 mm.

Clause 3. The method of clause 1, wherein the first zone is measuredwith a first plurality of A-scans of an OCT measurement beam and thesecond zone is measured with a second plurality of A-Scans of an OCTmeasurement beam.

Clause 4. The method of clause 3, wherein each of the first zone and thesecond zone is measured with a scanning OCT measurement beam.

Clause 5. The method of clause 4, wherein the scanning OCT measurementbeam moves along a first trajectory to measure the first plurality ofA-scans and a second trajectory to measure the second plurality ofA-scans.

Clause 6. The method of clause 3, wherein the first zone is measuredwith a first plurality of fixed measurement beams and the second zone ismeasured with a second plurality of fixed measurement beams.

Clause 7. The method of clause 6, wherein the first plurality of fixedmeasurement beams arranged to generate the first plurality of A-scansand the second plurality of fixed measurement beams is arranged togenerate the second plurality of A-scans.

Clause 8. The method of clause 3, wherein the first plurality of A-scansmeasures a first plurality of corneal locations distributed on a firstcorneal zone and the second plurality of A-scans measures a secondplurality of corneal locations distributed on a second corneal zone andwherein the first axial length corresponds to a difference between thefirst plurality of retinal locations and the first plurality of corneallocations and the second axial length corresponds to a differencebetween the second plurality of retinal locations and the secondplurality of corneal locations.

Clause 9. The method of clause 8, wherein a first plurality of axiallengths is determined and a second plurality of axial lengths isdetermined, the first plurality of axial lengths corresponding to firstdifferences between each of the first plurality of corneal locations anda corresponding retinal location, the second plurality of axial lengthscorresponding to second differences between each of the second pluralityof axial locations and a corresponding retinal location.

Clause 10. The method of clause 1, wherein the first zone substantiallyoverlaps with the second zone and optionally wherein substantial overlapcomprises at least about a 50% overlap between the first zone and thesecond zone.

Clause 11. The method of clause 1, wherein one or more of the firstmaximum distance across or the second maximum distance across comprisesa diameter.

Clause 12. The method of clause 1, wherein one or more of the first zoneor the second zone comprises an annulus.

Clause 13. The method of clause 1, wherein one or more of the first zoneor the second zone comprises an area.

Clause 14. The method of clause 1, wherein the first axial lengthcomprises a first axial length map and the second axial length comprisesa second axial length map and wherein the change in refractive errorcorresponds to a difference between the first axial length map and thesecond axial length map.

Clause 15. A system to measure a change in refractive error of an eye,the system comprising a processor configured with instructions toimplement the method of any one of the preceding clauses.

Clause 16. The system of clause 15, further comprising: a swept lightsource to generate an OCT beam and vary a wavelength of the OCT beam;and an interferometer coupled to the swept light source, theinterferometer comprising a measurement optical path and a referenceoptical path, the reference optical path comprising a first referencepath and a second reference path; wherein the first axial lengthcorresponds to a first difference between a first position of a corneaof the eye measured with the first reference path and the secondreference path measured at a first time and wherein the second axiallength corresponds to a second difference between a second position ofthe cornea measured with the first reference path and a second positionof the retina measured with the second reference path at a second time.

Clause 17. The system of clause 16, further comprising a detectorcoupled to the interferometer to receive a first interference signal anda second interference signal, the first interference signal resultingfrom light from the first reference path interfering with light from themeasurement optical path, the second interference signal resulting fromlight from the second reference path interfering with light from themeasurement optical path.

Clause 18. A system for measuring an axial length of an eye, comprising:a swept light source to generate a light beam and vary a wavelength ofthe light beam; an interferometer coupled to the swept light source, theinterferometer comprising a measurement optical path and a referenceoptical path, the reference optical path comprising a first referencepath and a second reference path; a detector coupled to theinterferometer to receive a first interference signal and a secondinterference signal, the first interference signal resulting from lightfrom the first reference path interfering with light from themeasurement optical path, the second interference signal resulting fromlight from the second reference path interfering with light from themeasurement optical path; and a processor coupled to the detector, theprocessor configured with instructions to determine the axial length ofthe eye in response to the first interference signal and the secondinterference signal.

Clause 19. The system of clause 18, wherein the first reference pathcomprises a first reference optical fiber and the second reference pathcomprises a second reference optical fiber.

Clause 20. The system of clause 19, wherein the first reference opticalfiber comprises a first length and the second reference optical fibercomprises a second length different from the first length.

Clause 21. The system of clause 20, wherein the first length correspondsto a first distance to a cornea of the eye and the second lengthcorresponds to a second distance to a retina of the eye, the firstdistance less than the second distance.

Clause 22. The system of clause 21, wherein the processor is configuredto generate an A-scan comprising a first peak corresponding to the firstdistance and a second peak corresponding to the second distance for eachof a plurality of sweeps of the swept light source.

Clause 23. The system of clause 22, wherein the first interferencesignal and the second interference signal are received together at thedetector for said each of the plurality of sweeps and wherein atransform of time varying intensity data sampled at the detector forsaid each of the plurality of sweeps generates a first peakcorresponding to the first distance and a second peak corresponding tothe second distance.

Clause 24. The system of clause 23, wherein the detector comprises abalanced detector.

Clause 25. The system of clause 22, wherein a single sweep of the sweptlight source generates a first peak and a second peak.

Clause 26. The system of clause 21, wherein the swept light sourcegenerates first frequencies and second frequencies at the detector, thefirst frequencies corresponding to the first reference path length andthe second frequencies corresponding to the second reference pathlength, the first frequencies less than the second frequencies.

Clause 27. The system of clause 21, wherein the first length remainssubstantially fixed and the second length remains substantially fixedwhile the swept light source sweeps through a range of wavelengths tomeasure the first distance and the second distance.

Clause 28. The system of clause 27, wherein the first length correspondsto a first optical path difference along the first reference opticalfiber and the second length corresponds to a second optical pathdifference along the second reference optical fiber, the first opticalpath difference less than the second optical path difference by anamount within a range from about 16 mm to about 26 mm and optionallywithin a range from about 18 mm to about 24 mm.

Clause 29. The system of clause 27, wherein the first distance of thefirst reference optical fiber is less than the second distance of thesecond reference optical fiber by an amount within a range from about 15mm to about 25 mm.

Clause 30. The system of clause 18, wherein the first interferencesignal comprises a first plurality of interference signals from a firstplurality of corneal locations and the second interference signalcomprises a second plurality of interference signals from a secondplurality of retinal locations.

Clause 31. The system of clause 30, wherein the light beam comprises aplurality of measurement light beams at the first plurality of corneallocations and the second plurality of retinal locations.

Clause 32. The system of clause 31, wherein each of the plurality ofmeasurement light beams illuminates a first corneal location and asecond retinal location.

Clause 33. The system of clause 31, wherein the first plurality ofcorneal locations and the second plurality of corneal locations remainssubstantially fixed when the swept light source sweeps across a range ofwavelengths.

Clause 34. The system of clause 33 wherein the plurality of measurementlight beams is arranged to measure the cornea at the first plurality oflocations and the retina at the second plurality of locations.

Clause 35. The system of clause 31, wherein the swept light sourcecomprises a plurality of swept light sources and the plurality ofmeasurement light beams is generated with the plurality of swept lightsources.

Clause 36. The system of clause 35, wherein the plurality of swept lightsources comprises a plurality of VCSELs.

Clause 37. The system of clause 36 wherein the plurality of VCSELscomprises two dimensional array of VCSELs.

Clause 38. The system of clause 18, further comprising a mirrorconfigured to scan a measurement beam from the measurement optical pathalong a retina of the eye.

Clause 39. The system of clause 38, wherein the mirror is configured toscan the measurement beam on the retina over a zone comprising a maximumdistance across within a range from about 0.05 mm to about 2.0 mm andoptionally within a range from about 0.1 mm to about 1.5 mm andoptionally wherein the maximum distance across comprises a diameter.

Clause 40. The system of clause 38, wherein the processor is configuredto generate a plurality of A-scans from measurement path at a pluralityof locations along the retina and wherein the processor is configuredwith instructions to determine the axial length in response to theplurality of A-scans.

Clause 41. The system of clause 38, wherein the mirror is configured toscan the measurement beam along a cornea of the eye while themeasurement beam scans along the retina of the eye.

Clause 42. The system of clause 41, wherein the processor is configuredto generate a plurality of A-scans for locations along the cornea andthe retina, each of the plurality of A-scans comprising a first peakcorresponding to the cornea and a second peak corresponding to theretina.

Clause 43. The system of clause 42 wherein the processor is configuredwith instructions to determine a location of the cornea in response tolocations of a plurality of corneal A-scan peaks and optionally anangular orientation of the eye with respect to the measurement beam inresponse to the locations of the plurality of corneal A-scan peaks.

Clause 44. The system of clause 43, wherein the processor is configuredwith instructions to determine an angular orientation of the eye inresponse to locations of a plurality of corneal A-scan peaks and aplurality of retinal and A-scan peaks.

Clause 45. The system of clause 44, wherein the processor is configuredwith instructions to determine the axial length of the eye in responseto the angular orientation of the eye.

Clause 46. The system of clause 41, wherein the processor is configuredto generate the axial length in response to the plurality of A-scans.

Clause 47. The system of clause 41, wherein the processor is configuredto scan the measurement beam along the cornea in a substantially annularpattern.

Clause 48. The system of clause 41, wherein, for each of the pluralityof A-scans, a retinal location of the measurement beam is on an oppositeside of an optical axis of the eye from a corresponding corneal locationof the measurement beam.

Clause 49. The system of clause 48 wherein an objective lens isconfigured to form an image of the mirror at a location between thecornea and the retina and wherein the measurement beam moves in a firstdirection on a first side of the image of the mirror toward the corneaand the measurement beam moves in a second direction on a second side ofthe image of the mirror toward the retina.

Clause 50. The system of clause 38, further comprising an objective lenslocated between the mirror and the eye, the objective lens configured tofocus a measurement light beam to a waist between the retina and a backsurface of a lens of the eye, the measurement light beam comprising aportion of the measurement beam.

Clause 51. The system of clause 50, wherein the objective lens isconfigured to form an image of the mirror in the eye at a locationbetween the cornea of the eye and the retina of the eye and optionallywherein the image of the mirror forms anterior to the waist in the eye.

Clause 52. The system of clause 18, wherein the processor is configuredwith instructions to generate an axial length map comprising distancesbetween a plurality of corneal locations and a corresponding pluralityof retinal locations.

Clause 53. The system of clause 18, wherein a zero optical pathdifference of the measurement beam is located within the eye between acornea of the eye and a retina of the eye and wherein the mirror isconfigured to scan a location of the measurement beam at the zerooptical path difference.

Clause 54. The system of clause 18, wherein the first reference pathcorresponds to a first zero optical path difference and the secondreference path corresponds to a second optical path difference.

Clause 55. The system of clause 54, wherein a first locationcorresponding to the first zero optical path difference of the firstreference path is located within about 10 mm of the cornea and a secondlocation corresponding to the second zero optical path difference of thesecond reference path is located within about 10 mm of the retina of theeye.

Clause 56. The system of clause 55, wherein the first location isscanned with a mirror and the second location is scanned with themirror.

Clause 57. The system of clause 50, further comprising one or more of avariable focus lens or a bifocal lens to focus the measurement lightbeam on the cornea and the retina.

Clause 58. The system of clause 18, wherein the swept light sourcecomprises one or more of a laser, a semiconductor laser, a movablemirror coupled to a laser, a micromechanically movable (MEMS) mirrorcoupled to a laser, a vertical cavity laser, or a vertical cavitysurface emitting laser (VCSEL), or a tunable VCSEL with MEMS mirrors.

Clause 59. The system of clause 58, wherein the swept light sourcecomprises the VCSEL, the VCSEL configured to sweep a range ofwavelengths with overdriving of a current to the VCSEL.

Clause 60. The system of clause 58, wherein the VCSEL is configured tosweep a range of wavelengths from about 5 nm to about 20 nm andoptionally from about 5 nm to about 10 nm.

Clause 61. The system of clause 18, wherein the swept light sourcecomprises a plurality of VCSELs.

Clause 62. The system of clause 18, further comprising a Purkinjeimaging system to determine a location of the cornea of the eye.

Clause 63. A system for measuring an axial length of an eye, comprising:an array of VCSELs configured to generate an array of light beams andsweep a wavelength of each of the light beams; an interferometer coupledto the VCSEL array, the interferometer comprising a measurement opticalpath and a reference optical path to generate a plurality ofinterference signals; an array detector coupled to the interferometer toreceive the plurality of interference signals; and a processor coupledto the detector, the processor configured with instructions to determinethe axial length of the eye in response to the plurality of interferencesignals.

Clause 64. The system of clause 63, further comprising a plurality ofoptical fibers coupled to the array of VCSELs on proximal ends of theoptical fibers and wherein distal ends of the optical fibers arearranged to transmit measurement light beams toward the eye.

Clause 65. The system of clause 63, further comprising a lens configuredto image the array of VCSELs inside the eye to generate the plurality ofinterference signals.

Clause 66. The system of clause 63, wherein each VCSEL of the array isconfigured to vary the wavelength with one or more heating or an indexchange of a gain medium within said each VCSEL.

Clause 67. The system of clause 66, wherein said each VCSEL of the arrayis configured to vary the wavelength without a MEMS mirror.

Clause 68. The system of clause 63, wherein each VCSEL of the array isconfigured to sweep the wavelength by an amount within a range fromabout 5 nm to about 20 nm.

Embodiments of the present disclosure have been shown and described asset forth herein and are provided by way of example only. One ofordinary skill in the art will recognize numerous adaptations, changes,variations and substitutions without departing from the scope of thepresent disclosure. Several alternatives and combinations of theembodiments disclosed herein may be utilized without departing from thescope of the present disclosure and the inventions disclosed herein.Therefore, the scope of the presently disclosed inventions shall bedefined solely by the scope of the appended claims and the equivalentsthereof.

1. A method of measuring a change in a refractive error of an eye, themethod comprising: measuring a first axial length of the eye from afirst zone of a retina at a first time to determine a first axial lengthof the eye, the first zone comprising a first maximum distance acrosswithin a first range from about 0.05 mm to about 2 mm; measuring asecond axial length of the eye from a second zone of the retina at asecond time to determine a second length of the eye at a second time,the second zone comprising a second maximum distance across within arange from about 0.05 mm to about 2.0 mm; wherein the change inrefractive error corresponds to a difference between the first axiallength and the second axial length.
 2. The method of claim 1, whereinthe first maximum distance across is within a range from about 0.1 mm toabout 1.5 mm and the second maximum distance across is within a rangefrom about 0.1 mm to about 1.5 mm.
 3. The method of claim 1, wherein thefirst zone is measured with a first plurality of A-scans of an OCTmeasurement beam and the second zone is measured with a second pluralityof A-Scans of an OCT measurement beam.
 4. The method of claim 3, whereineach of the first zone and the second zone is measured with a scanningOCT measurement beam.
 5. The method of claim 4, wherein the scanning OCTmeasurement beam moves along a first trajectory to measure the firstplurality of A-scans and a second trajectory to measure the secondplurality of A-scans.
 6. The method of claim 3, wherein the first zoneis measured with a first plurality of fixed measurement beams and thesecond zone is measured with a second plurality of fixed measurementbeams.
 7. The method of claim 6, wherein the first plurality of fixedmeasurement beams arranged to generate the first plurality of A-scansand the second plurality of fixed measurement beams is arranged togenerate the second plurality of A-scans.
 8. The method of claim 3,wherein the first plurality of A-scans measures a first plurality ofcorneal locations distributed on a first corneal zone and the secondplurality of A-scans measures a second plurality of corneal locationsdistributed on a second corneal zone and wherein the first axial lengthcorresponds to a difference between the first plurality of retinallocations and the first plurality of corneal locations and the secondaxial length corresponds to a difference between the second plurality ofretinal locations and the second plurality of corneal locations.
 9. Themethod of claim 8, wherein a first plurality of axial lengths isdetermined and a second plurality of axial lengths is determined, thefirst plurality of axial lengths corresponding to first differencesbetween each of the first plurality of corneal locations and acorresponding first retinal location, the second plurality of axiallengths corresponding to second differences between each of the secondplurality of axial locations and a corresponding second retinallocation.
 10. The method of claim 1, wherein the first zonesubstantially overlaps with the second zone and optionally whereinsubstantial overlap comprises at least about a 50% overlap between thefirst zone and the second zone.
 11. The method of claim 1, wherein oneor more of the first maximum distance across or the second maximumdistance across comprises a diameter.
 12. The method of claim 1, whereinone or more of the first zone or the second zone comprises an annulus.13. The method of claim 1, wherein one or more of the first zone or thesecond zone comprises an area.
 14. The method of claim 1, wherein thefirst axial length comprises a first axial length map and the secondaxial length comprises a second axial length map and wherein the changein refractive error corresponds to a difference between the first axiallength map and the second axial length map.
 15. A system to measure achange in refractive error of an eye, the system comprising a processorconfigured with instructions to implement the method of claim
 1. 16. Thesystem of claim 15, further comprising: a swept light source to generatean OCT beam and vary a wavelength of the OCT beam; and an interferometercoupled to the swept light source, the interferometer comprising ameasurement optical path and a reference optical path, the referenceoptical path comprising a first reference path and a second referencepath; wherein the first axial length corresponds to a first differencebetween a first position of a cornea of the eye measured with the firstreference path and the second reference path measured at a first timeand wherein the second axial length corresponds to a second differencebetween a second position of the cornea measured with the firstreference path and a second position of the retina measured with thesecond reference path at a second time.
 17. The system of claim 16,further comprising a detector coupled to the interferometer to receive afirst interference signal and a second interference signal, the firstinterference signal resulting from light from the first reference pathinterfering with light from the measurement optical path, the secondinterference signal resulting from light from the second reference pathinterfering with light from the measurement optical path.
 18. A systemfor measuring an axial length of an eye, comprising: a swept lightsource to generate a light beam and vary a wavelength of the light beam;an interferometer coupled to the swept light source, the interferometercomprising a measurement optical path and a reference optical path, thereference optical path comprising a first reference path and a secondreference path; a detector coupled to the interferometer to receive afirst interference signal and a second interference signal, the firstinterference signal resulting from light from the first reference pathinterfering with light from the measurement optical path, the secondinterference signal resulting from light from the second reference pathinterfering with light from the measurement optical path; and aprocessor coupled to the detector, the processor configured withinstructions to determine the axial length of the eye in response to thefirst interference signal and the second interference signal.
 19. Thesystem of claim 18, wherein the first reference path comprises a firstreference optical fiber and the second reference path comprises a secondreference optical fiber.
 20. The system of claim 19, wherein the firstreference optical fiber comprises a first length and the secondreference optical fiber comprises a second length different from thefirst length.